Cell.Expert via eBay offers the Carbon Fiber Pattern iPhone 6 Hard Case Cover in Black or Silver for $1.54 with free shipping. (A 5.5" iPhone 6 Plus case is available for a few cents more.) Outside of other eBay vendors, that's the lowest total price we could find for such a case by $3. It's made of carbon fiber and leather.

Note: This item ships from mainland China and may take three to eight weeks to arrive.