Tek Replay via eBay offers the refurbished 2.4-lb. Apple MacBook Air Intel Haswell Core i5 1.3GHz 11.6" Laptop, model no. MD711LL/A, for $559.99 with free shipping. That's $10 under our refurb mention from three weeks ago and the lowest total price we've seen in any condition. (It's $370 below the best price we could find for a new one today.) It features an Intel Haswell Core i5 1.3GHz dual-core processor, 11.6" 1366x768 LED-backlit display, 4GB RAM, 128GB SSD, 802.11n wireless, Bluetooth 4.0, Thunderbolt, USB 3.0, and Mac OS X 10.9 Mavericks.
A 30-day warranty applies, but it's unclear who backs it. Also, this item may show some signs of use.