Way to threadcrap, maybe the guy had a reason for selling his cube at the time.
I've seen the PS2 GTA for like $32 at Blockbuster, if you have 3 crap games, you can trade em in and get it for $5, plus get the credit you got for the games. As for the others, your best hope is to find them used (Try EB Games and use the codes to get discounts on em), although I'd get Digital Devil Saga while you can, as it seems to be getting tougher to find