Instant Replay Electronics via eBay offers the refurbished 2.4-lb. Apple MacBook Air Intel Core i5 1.6GHz 11.6" LED-Backlit Laptop, model no. MC968LL/A, for $509.99 with free shipping. That's $42 under our mention from Black Friday week and the lowest total price we've seen for this laptop. (It's also $64 under the best deal we could find for a used unit in good condition elsewhere.) It includes an Intel Sandy Bridge Core i5-2467M 1.6GHz dual-core processor, 11.6" 1366x768 LED-backlit LCD, 2GB RAM, 64GB SSD, AirPort Extreme (802.11n wireless), Bluetooth 4.0, Facetime camera, Thunderbolt, and Mac OS X 10.9 Mavericks. (No optical drive is included.)

Note: A 30-day seller warranty applies.