I don't understand why anybody rents games. It's - what - five bucks at blockbuster for a few days, and no average non-obsessive joe could finish most games in that time.
No, the best thing to do is limit yourself to older titles and buy 'em cheap - 15 - 20 bucks. There are many great games for the gamecube in that price range - wind waker, viewtiful joe, metroid prime, eternal darkness, animal crossing, and so on. I'm guessing it's even more so for the Playstation 2, with its huge library.
As to which console to get ... I dunno. I wish I'd gotten an x-box, because it has more games that interest me than the cube, and what I've seen of playstation exclusives don't do much for me. But the gamecube was _cheap_.