A lot of places up here (Canada...) are selling Gamecube bundles. Since I've seen the Canadian Best Buys advertising it, I assume it can't be all that much different in the US. But anyway, the bundles here consist of a Gamecube, Tales of Symphonia, and your choice of one more "Player's Choice" game... of which there is quite a selction (namely LoZ: Wind Waker, since a lot of people recommend that). Again, I don't know if there are any deals similar in the States, but there must be somewhere. If not, then yes, I would agree that you should go for a previously owned GCN--especially if you're planning to get the Revolution.
Anyway, as for games, in my totally biased opinion, you should get Tales of Symphonia, especially if you like RPGs as the Gamecube is a system that's rather lacking in that department... so TOS is definitely a good bet for that. As others have said, Super Smash Brothers Melee is another good one... basically since it's a game pretty much anyone can get, so it's great for when people are over and it's also just a great game all around. For racing... well, I myself didn't really enjoy Mario Kart Double Dash. It was just too complicated for a racing game. Other people seemed to like it, though, so it might not be so bad. :\ Paper Mario 2 (The Thousand Year Door) is another really good game. You don't even need to have played the first one, since this one is self-sufficient and it really is a good game. ^^; Pokemon Colloseum isn't that great... so I'd only suggest it if you're a mega Pokemon fan. x_o; It's fun, but it gets redundant pretty quickly imo...
Really, I'd suggest getting your 'cube with a few staple games (read as: Super Smash Brothers) and then go out and rent a few different games, figure out what you like, and then go it from there. ^^; That way if you don't like something, you aren't stuck with it and you've still got money for other games that you like more.