I didn't see these at all while at Comic Con, but that's easy to understand: it's a big place. Ultra big. Like, there was a full size recreation of the town of South Park across the street, and we didn't even notice it for the first two days.
Anyways, these cards started showing up on Ebay and, after noticing the address on one and dialing in, I discovered there's a real live version of the collectible card game "Mystic Warriors of Ka'a" up on facebook!
While it seems to be a little buggy, it's kind of fun, as the characters from the show appear to teach you the rules and then, play against you.