I've been collecting and flipping cards for years. Here are the most expensive mistakes I see people make:

1. Only checking one marketplace. eBay isn't always the cheapest. TCGPlayer, CardMarket, local shops, and auction houses all have different pricing. The spread can be 15-40% on the same card.

2. Buying on hype days. When a new set drops or a card trends on social media, prices spike 20-50% within hours. If it's not a chase card, wait 2-3 weeks and the price normalizes.

3. Ignoring condition grading. The difference between NM and LP on a $50 card can be $15+. Know exactly what condition you're paying for before clicking buy.

4. Not tracking price history. A card listed at $30 might have sold for $18 last week. Without price history data, you're flying blind.

5. Missing auction snipes. Some of the best deals are auctions that end at weird hours with low bid counts. If you're not watching, you're losing.

I built CardSnipe to solve all of these. One tool that searches every major marketplace, tracks price history, and lets you buy or bid from a single dashboard.

If you're tired of overpaying, check it out.