"Will this resell?" is the question behind every buy. Hype, a sellout and a scary-looking price on a listing all feel like answers, but none of them are. We look at three kinds of data before we call a product, and we do it the same way for Lego, vinyl and Monster High dolls. Here is the process, so you can run it yourself.
Step 1: Check Amazon sales trends
Amazon shows you how a product is selling before you ever look at eBay. For the category we're checking, we look at:
- Best Sellers Rank. A rank that is low (better) and holding steady means people keep buying. A rank that jumps around, or collapses a few days after a release, usually means a one-time spike.
- "Bought in past month." Amazon shows this on many listings. A big number tells you the product moves. A missing or small number tells you to be careful.
- Price over time. If the price has stayed flat or risen, demand is holding. If it keeps dropping, Amazon or other sellers are competing the price down.
- Who is selling it. Is Amazon itself the seller, or only third-party sellers? When Amazon sells a product at a fixed price, that price sets a ceiling for everyone else.
- Stock. A listing that keeps going out of stock is a hint that supply is tight. A product that is always in stock is not scarce.
Amazon matters most for products it sells directly, like Lego sets and in-print vinyl. It shows what regular shoppers will pay and how fast they're buying. It does not tell you what a collector will pay for a sold-out item. That's what eBay is for.
Step 2: Check eBay sold listings, for volume and for price
This is the step that decides most calls. On eBay, filter to sold (completed) listings, not active ones. Asking prices are wishes. Sold prices are what people actually paid. We look at two numbers:
- Volume: how many sold. Count the sales in the last few weeks. A product that sold 40 times in a month has real demand. One that sold twice has a price you can't trust, because two sales can be flukes.
- Price: what they sold for. Look at the sold prices together, not the single highest one. We use the average of the newest matching sales, so one lucky outlier doesn't mislead us.
The sales have to be for the same product. For each item we check:
- Same version. A first pressing and a repress of the same record are different products. So are two color variants, a signed copy and an unsigned one, or a new doll and a loose one.
- Same condition and quantity. Sealed and new, one at a time. Lots, bundles and graded or opened items are left out.
- Recent. Last few weeks, not last year. Prices move fast after a release.
That's how the Preorders & Releases page is built. For each product we average the newest matching sales, up to 10 from roughly the last 45 days, and when there aren't at least 3 clean matches we show no price at all instead of guessing.
Step 3: Count how many other people are selling it
Demand is only half the story. The other half is supply: how many sellers are competing for the same buyers. On eBay, look at the number of active listings for the exact product and compare it with how many sold.
- Few listings, many sales. Buyers are waiting, and listings sell quickly. This is the best case.
- Many listings, few sales. The market is crowded. Even if the price looks good, you'll be waiting, or you'll cut your price to be noticed.
- Falling listing count. If active listings are disappearing, supply is running out and prices often follow.
A simple way to think about it: if 40 sold last month and 10 are listed now, the item clears fast. If 40 sold and 200 are listed, you're one of a lot of sellers and a long wait.
A worked example: a Monster High doll
On our Preorders & Releases page, a recent Monster High Dawn of the Dance reproduction doll retailed for $32.99. As of October 2, eBay showed a $71 average across the 10 newest matching sales for a single doll.
Here is the arithmetic. eBay's fee is 13.6% plus $0.40 per order (see our reseller fees guide), so at $71 you keep about $61 before shipping, against a $32.99 cost. That's a healthy gap, and 10 recent sales is enough volume to trust the number. Shipping and packaging come off the top, and the listing count would be the next thing to check before buying many.
One data point isn't a promise. Prices move as more copies reach buyers, which is why we recheck before we call something and why we avoid buying more than the market can absorb.
Putting the three steps together
| What we check | What it tells us | Good sign |
|---|---|---|
| Amazon trends | How regular shoppers buy it | Steady rank, strong "bought in past month", stock goes in and out |
| eBay sold volume | Whether anyone is actually buying | Dozens of recent sales, not a handful |
| eBay sold prices | What they pay | A tight range well above cost plus fees |
| Other sellers | How crowded the market is | Few active listings compared with sales |
When all four line up, it's a strong candidate. When one is off, we either skip it or buy fewer. For Lego, the same math decides whether a retiring set is worth holding, like in our Iron Spider-Man Bust breakdown. For vinyl, the pressing and variant matter most, as in our guide on where to sell vinyl records.
Common mistakes
- Using active listings as the price. Look at sold listings only.
- Trusting the highest sale. One outlier isn't the market. Use the average of several.
- Mixing versions. The wrong pressing, color or condition throws every number off.
- Forgetting fees and shipping. The price you see is not what you keep.
- Ignoring competition. A good price with 200 competing listings can still be a slow flip.
Do it with a team
Doing this for every drop takes time, and the best calls are made in the first minutes. In our Discord, our team runs these checks and posts the calls, so you don't have to dig through eBay yourself.
Friends & Family is an independent reselling community. This article is educational, not financial advice, and resale prices are not guaranteed.