CowBoom offers the refurbished Apple iPad Air 32GB WiFi Tablet in Space Gray, model no. MD786LL/A, for $459.99. Apply coupon code "14681903" to cut the price to $399.99. With free shipping, that's $145 below today's mention of a new model bundled with a dock, still available, and the lowest total price we've seen. (It's also $109 below the cost of a refurb elsewhere.)
Note: No warranty information is available. Also, this used unit may be missing parts or accessories and have dents or scratches.