Altatac via eBay offers the refurbished Apple iMac Intel Core i3 3.06GHz 21.5" 1080p Desktop, model no. MC508LL/A, for $449.95 with free shipping. That's the lowest total price we could find by $37. This iMac features an Intel Core i3-540 3.06GHz dual-core processor, 21.5" 1920x1080 (1080p) LCD, 4GB RAM, 500GB hard drive, ATI Radeon HD 4670 256MB graphics card, SuperDrive DVD Burner, AirPort Extreme (802.11n wireless), Bluetooth 2.1+EDR, iSight webcam, wireless keyboard and mouse, and Mac OS X 10.6 Snow Leopard.
Note: A 90-day warranty applies although it's unclear who backs it.