Every money-losing lot I've ever bought had one thing in common: I did the math after winning the auction instead of before bidding. The fix was embarrassingly simple. I built a calculator, made a rule that I never bid without running it, and the bad buys mostly stopped. That calculator now lives on this site, free: the Card Flip Calculator.
What it actually calculates
The number that matters isn't the auction price. It's landed cost per card versus net revenue per card, and both sides have layers people forget. On the cost side: the lot price in its original currency (yen, usually, for me), the proxy service fee, international shipping, and the customs assessment that Canada Post loves to spring on you. On the revenue side: your target sold price, minus eBay's final value fee on price plus shipping charged, minus the $0.30 per-order fee, minus postage and packaging. The calculator stacks all of it and hands you one number: profit or loss on the lot.
The feature that saves the most money
It's the sell-through slider. Every lot buyer's spreadsheet assumes every card sells; no lot I've ever bought has actually done that. My real sell-through on mixed lots runs 50–60%, so the calculator shows profit at 60%, 80%, and 100% side by side. The rule that falls out of it: if a lot is only profitable at 100% sell-through, it isn't profitable. That single sentence has vetoed more of my bids than any other filter.
Built for the cross-border reality
Because I buy in Japan and sell in Canada, the calculator handles five currencies with live exchange rates, knows eBay.ca's trading card fee structure (13.25%, or 11.925% with Top Rated Seller Plus), and includes fields for proxy fees and customs that most profit calculators ignore. There's also a break-even readout: the minimum average price per card where the lot stops losing money, which is a useful sanity check against what the cards actually comp for.
How I use it, start to finish
- Find a lot worth considering and estimate the visible hits from the photos (my lot evaluation guide covers this).
- Enter the lot price in its currency, the quantity, and my standard import costs.
- Set the average target price conservatively, based on sold comps, not asking prices.
- Drag sell-through to 60% and look at that number, not the 100% one.
- If it's green at 60%, I set my maximum bid and stop there. If it's red, I close the tab.
It saves lots too, so you can compare a Buyee auction against a local pickup side by side. Everything runs in your browser and nothing gets uploaded. Try it here, I hope it saves you from a bad lot or two.