GameFly ftw.
With your level 3 - 10% discount and the $5 coupons they throw you every 3 months, you can walk away with some real steals.
I got last year:
Mirrors Edge, Red Faction, Silent Hill Homecoming, GRID, Riddick, Battlefield Bad Company - all for around $9 each. Turok and Fracture for $7 each. Battlestations Pacific for $11.50.
Not only do they have some really good prices sometimes, every disk case and manual is brand new, and I've never had a faulty disk either. And their return/refund policy in my experience has been no-hassle.