Someone who collects baseball cards, rare coins, stamps, artwork, or anything else that sets them aside from mainstream, non-nerdy people, while also rejecting traditional trappings of nerdom.
The wanna-be nerd, for instance, will have nothing to do with fantasy, role-playing games, and science fiction; in fact, they may actually be unable to tell apart such great examples of nerdy sci-fi as Star Wars, Star Trek, Battlestar Galactica, and/or Doctor Who.
Tim: "Why didn't you invite Paul to the Star Wars party? He's a nerd, too."
Bob: "No way, man, he's just a wanna-be-nerd...he spends all his time blogging about his baseball cards and he's never even SEEN Star Wars!"