Every single thing I buy starts with the same little voice in my head going “ooh, what’s that?”.

And then, somewhere between spotting it and paying for it, that same little voice has to decide whether the thing is coming home with me or staying right where it is.

That decision — buy it or leave it — is the whole game. Get it right often enough and you’ve got a business. Get it wrong often enough and you’ve got a garage full of stuff your other half keeps asking you to “do something about”.

So this one’s about how I actually decide what to buy and what to leave. Not a tidy little checklist I made up to sound clever, but the real running maths that goes on in my head at 7am in a muddy field with a coffee going cold in my hand.

If you’re just starting out and you currently buy basically everything that looks “a bit good”, this is for you. By the end you’ll have a proper filter — and the confidence to walk away.

Right, let’s get into it.

The calculation starts before I’ve even reached the stall

Here’s the bit most beginners don’t realise. By the time I’m actually standing at the table, half the thinking is already done.

Something catches my eye from a few feet away. And in the seconds it takes me to walk over, my brain’s already running the numbers.

Have I had this before? If I have — what did I sell it for? How long ago? Was it the exact same item, in the same condition, or is this a slightly different version that changes everything?

By the time my hand’s reaching for it, I’ve already got a rough ceiling in my head for what I’m willing to pay. I haven’t picked it up yet and I’ve half-decided the deal.

That’s not a brag. That’s just reps. Do this every weekend for a couple of years and your brain builds its own little pricing database. You stop “having a think” and start “knowing”. The walk over IS the research.

Then I pick it up — and the real maths kicks in

Now I’ve got it in my hand, the proper numbers start.

How much is this actually worth, sold, today? Not what some hopeful soul has it listed for — what it’s genuinely selling for.

Then straight away: what’s postage going to cost me? Because a heavy or awkward item can quietly eat your whole profit before you’ve even started.

Then: what am I left with after fees? eBay takes its cut on the item AND the postage combined, so I’m doing that sum in my head too.

And while I’m doing all that, my eyes are scanning the rest of the stall. Is there anything else here I’d want? Because if there is, I’m not buying one thing — I’m building a bundle, and a bundle is where you get your best price.

Only then do I ask the magic question: “How much do you want for it?”

Whatever number comes back lands in one of three boxes. A good price — happy days. An okay price — workable, but now I’m definitely asking about a bundle to sweeten it. Or a “put it down and walk away” price — too far apart to bother, so I smile, say thanks, and move on.

No drama, no hard sell. Just three boxes.

The 10x rule (and when I let it slide)

Here’s the number that actually governs everything: I’m aiming to 10x my money.

I’ll happily settle for 7x after all the fees are paid — but 10x is the target I’m buying against.

So a £2 item needs to be netting me at least £14. A £1 item needs to clear £7. And so on up the scale. If the maths doesn’t get there, the item goes back on the table. Simple as that.

But — and this matters — that multiplier comes down as the price goes up.

On a higher-value item I’ll happily take less. I could pay £20 for something and be made up with a 3x. Because 3x on £20 is £40-odd profit on one item, and that’s a very different conversation to 3x on a 50p toy.

The percentage drops but the actual pounds go up. And it’s the pounds that pay the bills, not the percentage. Beginners obsess over the multiple. After a while you start thinking in cold, hard take-home instead.

The thing nobody warns you about: shelf space

Here’s a lesson the field will never teach you. You only learn it when you get the stuff home.

In the moment, space doesn’t enter my head. But the second I’m back and trying to find somewhere to put it all, the real cost shows up.

What I’m actually balancing is profit against the room it takes up.

I would much rather have something I can stock fifty of in the same space, each one netting me a tidy 10x, than one big lump that only does 3x and hogs an entire shelf on its own.

Profit per item is only half the picture. Profit per square foot is the half that decides whether your operation can actually grow — or whether you’re just slowly burying yourself.

Which brings me neatly to the stuff I now walk straight past.

What I leave behind now (that I’d have grabbed two years ago)

Mugs. I walk past nearly all of them.

The exception is Disney mugs, if the design looks genuinely different from the bog-standard Primark or supermarket ones. You can tell almost instantly — flip it over and the bottom tells you everything. But a normal mug? It’s heavy, it’s fragile, postage is a nightmare, and the ceiling’s about three quid. Hard pass.

And electronics — this one might surprise you, because the margins can be lovely.

But here’s the problem. The odds that the thing works 100% are never as good as they look on the table. And a faulty item doesn’t just lose you the sale — it comes BACK to you. Return postage, a grumpy buyer, your feedback taking a knock, and you’re now sat on a broken thing you’ve paid twice to handle.

On top of that, electronics tend to be bulky. So you’ve got high risk AND high shelf-cost. For me, it’s just not worth the headache most of the time.

None of this was obvious to me early on. I learned every one of these the boring way — by getting it wrong first.

Trust the gut — it’s just experience wearing a disguise

This is the big one, and it’s the hardest to teach because it sounds a bit woolly. But stick with me.

If I pick something up, I like it, the numbers should work… but the price just doesn’t feel right? I put it down and walk away. Every time.

A year ago I wouldn’t have. A year ago I’d have talked myself into it, paid a bit too much, and made less profit for more hassle. Now I just trust the feeling.

Because here’s the thing — that “gut feeling” isn’t magic. It’s not mystical. It’s hundreds of past deals compressed into an instant. Your brain has seen this situation before and it’s quietly telling you how it usually ends. Trusting your gut is just trusting your own experience, before your conscious brain has caught up enough to explain why.

The more reps you put in, the louder and more reliable that voice gets. And once you learn to actually listen to it, you stop making the daft buys.

Let me show you exactly what it looks like when it goes right.

The £8 punt that turned into £700+

A few weeks back, Sayers Common. There’s a pile of what looked like really old maps just shoved on the floor, dumped in among the usual bric-a-brac.

So I crouch down, pick a few up, have a proper look. They’re old. Properly old. I’m thinking there’s maybe twenty of them.

I ask the lady how much. “Tenner,” she says.

Now, this was one of those moments where I genuinely wasn’t 100% sure. The gut wasn’t screaming yes — but it wasn’t screaming no either. So I did the one thing that costs nothing: I asked if that was firm.

“Eight quid,” she says.

Sold. Eight pounds, into the boot, off I went.

Got home, properly counted them out — and there weren’t twenty. There were forty-eight. Every single one of them either WW1 or WW2 era.

A quick valuation session and I’m sitting there realising this dusty little pile is potentially worth over seven hundred quid, collectively.

Let’s do the maths on that, because this is the bit I love.

• In: £8 for the whole pile of 48 maps.
• First sale: within four hours, one buyer took five of them in a single go for £180.
• Second sale: two weeks later the same buyer came back for another two at £50.
• So far: £230 banked from just seven of them — with around forty still sitting there waiting.

From an eight-pound punt. THAT is what following your gut looks like. The gut said “have a proper look at these”, and I listened.

And the mistakes? Oh, I’ve made plenty

I’d be a liar if I made out it’s all £700 map piles. Let me tell you what I get wrong, because the mistakes taught me more than the wins.

I keep buying comics. I know I do it. Even after the Ford pickup — six thousand comics for £200, which did really well — I still can’t walk past a box of them. I try to be disciplined now and only buy proper runs rather than random singles, but it’s a weakness and I know it.

Then there’s the volume stuff that nearly broke me. The ten thousand football programmes I drove halfway up the country for. Did I make money? Yes. But they took over the entire garage and took MONTHS to shift. The profit was real but the misery was also real.

And the absolute worst one: thirty thousand Magic: The Gathering cards. Can’t even remember where I drove to collect them. They weren’t worth much, I shifted them for double what I paid, fine — except “double” meant driving all the way to Plymouth and back to hand them over.

I was literally round the corner from the buyer when I pulled over, just to check the boxes weren’t going to tip over when I opened the boot.

Opened it. One box went. About two hundred cards took flight in the wind.

There I am, a grown man, chasing Magic cards across a Plymouth side street. If you ever needed proof that “I made a profit” and “this was a good buy” are two completely different sentences — that’s it, flapping down the road.

How my buying’s changed (and why yours should too)

When I started, I was the 50p-to-£4 guy. Pick it up for pennies, flip it for a few quid, feel clever.

And honestly? It wasn’t sustainable. The effort per pound was brutal. You’re doing the exact same photographing, listing, packing and posting on a £4 item as you are on a £40 one — for a tenth of the reward.

So I deliberately pushed my average up. These days my average selling price hovers around the £20 mark, and the whole balance sheet looks healthier for it.

That’s the rule I’d hand any beginner who’ll listen: as soon as you can, raise your floor. The stuff I buy now basically has to land at an ASP of at least £20 after fees — so I’m looking for items I can realistically sell around the £25 mark and up.

Fewer, better items. Same work, more reward. It’s the single biggest lever you’ve got.

So — buy it or leave it?

If I had to boil the whole lot down to one line, it’s this: the maths gets you in the door, but the gut closes the deal.

The best buy of the day is very often the one you didn’t make.

Run the numbers — value, postage, fees, the multiple, the shelf space. If they don’t work, it’s an easy no.

But when the numbers are borderline and that quiet voice is telling you something? Listen to it. It’s not magic. It’s every deal you’ve ever done, whispering the answer before you’ve worked it out the slow way.

And don’t be scared to walk away. The leave-it pile costs you nothing and saves you a fortune.

If you want to see what actually clears the bar, have a nosey at what I’ve got listed right now over on eBay under icarbootsale — that’s the buy-it pile, the stuff that passed the test. The leave-it pile, you’ll be pleased to hear, stayed in the field.