Try Game Stop. They have a holiday bundle for $299.99 and you get a $60 GC back. It comes with a 250GB hard drive, one controller, 2 games (Fable 2 or 3 and Halo Reach) and 3 months of XBOX Live.
They also have a Kinect on sale for $ 109.99 which also comes with 2 games, Kinect Adventures and Gunstringer. Gunslinger also has Fruit Ninja on it, which is a popular phone app.
So if you use that gift card to pay for the Kinect system, it'd cost you $349.98 plus tax for everything which is $50 cheaper than the Kinect bundle you can buy and you get 2 more games.
Trust me, I work there.
Hope I helped!