The Good Blokes via eBay offers the OEM Belkin Grip Candy Sheer Case for iPhone 5/5S in Gravel Smolder for $4 with free shipping. (One Source Wireless via Amazon has it in Grey for a few cents more for Prime members.) That's tied with our mention from last week, the lowest total price we could find by a buck, and a very strong deal for such a name-brand case. This case is made from flexible easy-grip TPU material.
Note: It's not guaranteed for delivery by Christmas.