I'm not very much of a completist either. I don't have the money to be, actually. The only system I'm close to completing is Odyssey2... I have every U.S. game (complete in box) except Power Lords, which I probably will never get because of the cost. I have the homebrew Multicart, so I can play the game, at least.

My "least" complete collection is N64... I have a system but no games! :)