Found both titles new at Shopko on clearance. Only 1 copy of MP3 (xbox version was $14.99) and only 2 copies of De Blob 2. Probably widely YMMV, but I figured if anyone was interested they could try their local Shopko. Marshall, MN is where I found mine. I don't know if they would price match the xbox counterpart of MP3 or if they would for some reason have more in back.
Anyways, I hope this helps someone and good luck!