The Baseball Card Movie is a nice nine-minute film that introduces the viewer to a world where adults pay up to $500 for a pack of cards (aka cardboard crack) and act very superstitiously about opening them.
Thw whole sports memorabilia thing is an odd world. There's a story about major league pitcher Barry Zito buying his own autographed cards on eBay:
He once made it a practice to buy his own autographed baseball cards on eBay; when asked why he bought them at auction for high prices rather than acquiring unsigned cards and signing them himself, Zito replied, "Because they're authenticated."
Possibly apocryphal but Zito would likely have a difficult time selling self-signed cards because they're not authenticated.