I was just looking at all the cheap PS2 games on gamestop.com. It's like a gamer's heaven. I've wanted to try MDK2 also. It looks like it'll be fun, maybe just outdated. I've been eyeing Death by Degree and unlimited saga.
My list of bargain PS2 games that every PS2 owner should own/have played/are interesting:
Maximo (get this - it's not as polished as the sly series but I think it blends action/platforming very well).
Viewtiful Joe
Viewtiful Joe 2
Mark of Kri
Onimusha
The Getaway (frustrating controls though)
Haven (too much variety but the story grew on me, too bad for the cliffhanger ending)
NBA Ballers
Galerians Ash (camera might make you dizzy, like Kingdom Hearts's camera, like akira story)
Lotr: Two Towers (I thought this was more fun than returnof the king, though a lot shorter)
The Thing
Okage
Primal (buggy but very interesting)
Nightshade (love this game, I need to find a copy of shinobi).
Jak and daxter
After those:
XIII, Metal Arms are both good straightfoward FPS.
dead to rights - everything's outdated but it's a simple shooter.
Kya - I need to change my pricegrabber review to maybe three stars. Early on it seems fun but after several levels, the fun has worn off and the story seems to have been forgotten.
Future Tactics - strategy game that plays out a bit too slow. I wish it was a Shining Force game.
skip these games unless you have run out of games to play:
Musashi - even at $7.99 I think this is over priced. And the voice acting is horrible.
Cygirls - controls fine but boring and unoriginal.
Blowout - 2d shooter but got bored after playing for an hour. Graphics aren't bad though.