Folklore - It is $30 at Gamestop. Very cheap and well worth it for the story, art style, and music alone.
Heavenly Sword - The price has dropped to $30 used at Gamestop for ONLY this week. So I would reccomend getting.
Uncharted - A very fun and awesome game from Naughty Dog.
Ninja Gaiden Sigma - if you are a fan of hardcore 3d action games.
Super Stardust HD and PixelJunk Monsters are must buys on the PSN.
(Note: if you plan on getting any games from Gamestop, I reccomend using this coupon. Very good deal.)