I recently surpassed 100 PS2 games in my collection and there are still a ton I'd like to try. I think $53 is a good price, just be prepared for it to look pretty bad on an HDTV, if you have an old SDTV on hand I'd use it. Also be prepared for a lot of the games to hace aged poorly, but that's always the case with old-school gaming, plenty of them are still great.
For original Xbox, that's a tough one, it can look better in HD and the multiplatform titles will look better but are usually a little harder to find. I bought one for the first time myself a couple years ago and didn't find it very necessary since 360 can play a lot of the games anyway, and many I was looking forward to got next-gen re-releases, like Doom 3 and Far Cry: Instincts.