MegaMacs offers the refurbished 2.4-lb. Apple MacBook Air Intel Core i5 1.6GHz 11.6" LED-Backlit Laptop, model no. MC968LL/A, for $549.99 plus $2 for shipping. That's $218 under our September mention of a new one (this one's refurbished) and the lowest total price we could find for a used one by $110. It includes an Intel Core i5-2467M 1.6GHz Sandy Bridge dual-core processor, 11.6" 1366x768 LED-backlit LCD, 2GB RAM, 64GB SSD, AirPort Extreme (802.11n wireless), Bluetooth 4.0, Facetime camera, and Thunderbolt. (No optical drive is included.) Deal ends December 3.

Mote: A 30 day warranty applies, but it's unclear who supports it. Also, this refurb has an OS is installed on this system, but it's unclear which version.