CowBoom offers the used Microsoft Xbox 360 S 250GB Console, model no. 87429P, for $99.99 plus $5 for shipping. That's tied with our mention from three weeks ago and the lowest total price we've seen. (It's a current low by $175.) It features 250GB internal memory, WiFi, and a wireless controller.
Note: No warranty information is provided. This used unit may be missing parts or accessories and have dents or scratches.