A4C via eBay offers the refurbished OtterBox Defender Case and Holster for iPhone 6/6S in Glacier Gray/White, model no. 77-50207, for $17.99 with free shipping. That's tied with March's refurb mention and $2 under the lowest total price we could find for a new unit now. It features a built-in screen protector and rubberized exterior.
A 90-day A4C warranty applies.