Most of the games you don't need the hard drive for. 90% of the 360 library works with the memory card (I *think* I read GH works without but maybe I was thinking of a different game). Plus you can buy any of the original xbox games - which need no hard drive - for the same price as the PS2 games.
You are right, sooner or later you will end up getting the hard drive though.
There is no doubt the PS2 is still a great viable gift. I just don't think getting it at $130 bucks is the way to go

. At least on ebay if you spent ~that much you could get a handful of games and extra controllers.
Then again, if I was going to get and older get console I'd buy myself a Dreamcast.