CowBoom offers the used Microsoft Xbox 360 250GB Slim Console for $119.99. Coupon code "XBOX20250" cuts it to $99.99. With free shipping, that's $10 under our November mention of a used unit and the lowest total price we've seen for any 250GB Xbox console. (For further comparison, it's currently $150 under the best we could find for a new one.) It features a 250GB hard drive, 802.11n wireless, and HDMI.
Note: No warranty information is provided and this used unit may have dents or scratches and be missing parts or accessories.
Before you spend another dollar on items and services like these, check with your public library. You will likely be surprised by what it offers for free.