As one of its daily deals, CowBoom offers the used PlayStation 3 500GB Slim Console, model no. CECH-4001C, for $109.99 with free shipping. That's $15 under our mention of a used unit from three weeks ago and the lowest total price we've seen. (It's also $110 under the best price we could find for a new unit.) It features a built-in Blu-ray player, 3D support, built-in WiFi, and HDMI output. Deal ends today.
Note: No warranty information is provided. Also, this used unit may have scratches or dents and/or be missing accessories, such as a controller.