TekReplay via eBay offers the refurbished 3-lb. Apple MacBook Air Intel Core i5 1.7GHz 13.3" LED-Backlit Laptop, model no. MC965LL/A, for $499.99 with free shipping. That's the best total price we've seen for this model in any condition. (It's a current low for a refurb by $93.) It features an Intel Sandy Bridge Core i5-2557M 1.7GHz dual-core processor, 13.3" 1440x900 LED-backlit LCD, 4GB RAM, 128GB SSD, AirPort Extreme (802.11n wireless), Bluetooth 4.0, Facetime camera, Thunderbolt, and Mac OS X 10.7 Lion (eligible for free upgrade to Yosemite).
A 30-day TekReplay is included but it's unclear who backs it.