I build Flipzi, a price API for trading cards, on my own. It began as a collection tracker, where I kept running into the same problem: a card's visible price usually describes what a seller wants, not what a buyer paid.

That distinction became the central design decision behind the API. A card has at least two useful prices, and applications need to know which one they are showing.

This tutorial retrieves both values for the same card, checks the evidence attached to them, and exposes the same workflow to an AI assistant through MCP.

Two prices

A card listed at EUR 2,275 tells you what a seller hopes for. It does not tell you what buyers pay.

For a collection tracker, store tool, or pricing bot, the second number is often more useful, and harder to calculate. Completed sales are spread across eBay sites in different countries and currencies.…