We bought a PlayStation2 for Christmas. I really looked and thought long and hard about which system. True, there are a lot more games for young kids on the GameCube, but it seemed to me there were plenty I was okay with for PS2, lots of racing type games, DDR (great exercise for me!) and some other cute stuff. This seemed like a system that we could use long term, that as the kids (and we) want to try new games they had a great selection. We also have bought many very inexpensive PS1 games, which can be used on this too, which have been great for the kids, and they have been less than $10 a game.
We bought our system at Sam's Club. It came with the console, two controllers, a memory card, two games (that were ones we wanted - Sly Cooper is great fun and family friendly) which was about everything we would have bought. It was less than $300 (still a bit of an ouch), but other than a game here and there I haven't had to get anything else.