CowBoom offers the used Apple iPad Air 16GB WiFi Tablet in Space Gray, model no. MD785LL/A, for $249.99. Coupon code "Air15715" drops it to $219.99. With free shipping, that's $50 under our January mention and the lowest total price we've seen for any iPad Air. (It's also $58 below the best price we could find for a used or refurbished unit elsewhere.)
Note: No warranty information is provided. Also, these are used items and may have scuffs, surface scratches, dents, or other cosmetic blemishes, and may be missing parts/accessories.