Custom battle card printing service

My son found a Yu-Gi-Oh card customizer and has been making his own cards. Virtually, anyway. The generator end is easy, nearly a cookie-cutter ImageMagick app. The interesting idea comes from (1) providing a gallery interface and (2) being able to select groups of cards to be printed and mailed to you.

Obvious downside: copyright. Ah, well. It's still a good idea, and if you're not aiming for big money, it would be a fun project.