I personally don't think there's any question on this one - Kmart.
Question is: how LOCKED IN are you at BB? If you can unlock yourself, do it and go with Kmart.
The game is at full price, but it comes with a $30 Spend It Your Way credit and another $10 credit for Lord of the Rings: War in the North. Best if you want LOTR, obviously (would be $19.99 new AND comes with a $20 credit, I believe), but getting anything else will be $30 off - nothing to sneeze at.