TechRabbit offers the refurbished Logitech Ultra-Thin Keyboard Folio for iPad Air, model no. 920-006336, for $12.99 with free shipping. That's $22 under the best price we could find for a new one. It protects your iPad from drops, falls, dust, dirt, and wear-and-tear.
A 1-year warranty applies, although it's unclear who backs it.