If you try out Suikoden, don't start on IV. It's pretty bad as far as a Suikoden game go and may turn you off on the series. V and III are much better games, V probably morese than III, and both shouldn't be that expensive to buy off ebay or something. Suikoden I probably goes for $30-$50 and II for maybe $50-$100, so it can be expensive getting into this series if you end up liking it. Suikoden I is on PS3's Playstation Newtork as well, but $400 + $6 to buy the game is a lot more than $30-50 off ebay.
The only games I can think of not mentioned so far that I would really recommend (and are playable on either the PS2 or 360) are Grandia and Breath of Fire III for the PS1. I have no idea what they would cost or how hard they would be to find, though. And in case you somehow have means to play on a Dreamcast or Gamecube, Skies of Arcadia is another RPG I've really enjoyed. (infacti'mplayingthatrightnow...)
Pokemon Ranger saves the day again.
