CowBoom offers the used Microsoft Xbox 360 4GB Slim Console, model no. RKB-00001, for $49.99. Coupon code "X3604010314" cuts the price to $54.99. With free shipping, that's $30 below our August mention of a used model and the lowest total price we've seen. (It's a current low by $135 for a new model.) Features include 4GB internal memory and WiFi.
Note: No warranty information is available (a product protection plan is offered for additional cost). This used unit may be missing parts or accessories and have dents, scratches, or other cosmetic blemishes.