PixelJunk Racer, Shooter, Eden, and Monsters are a whopping 90% off, or one dollar each. Shooter 2, Sidescroller, and Monsters Deluxe (for PSP) are 50% off, or $5 each.
I bought all of the PixelJunk games I didn't already have, except Monsters Deluxe. You really can't go wrong with Eden and Shooter 1 and 2.