Stopped by the local Blockbuster to checkout the b2g1 on used games and came across GTA: Episodes from Liberty City for 30$. It didn't come with the original case but it came with everything else (I switched the case from my old XBL compilation disk anyway). There was only one copy in the store...
I recently picked up Dark Sector at EB games in Winnipeg for 8.99$. Pretty decent game and well worth your pocket change. Seeing how Blockbuster rentals are somewhere close to 9 bucks anyway why not just buy it?
Yesterday I picked up a copy of TMNT for $3 at the local EB.
Even if you play it for like an hour it'd still be worth it. Also, easy easy gamerscore :P