Zagerz offers the OtterBox Commuter Series Case for iPhone 5/5S in Black or Blue for $10.99 with free shipping. (Search for "Commuter" to find it.) That's $4 below last month's mention and the lowest total price we've seen. (It's a current price low by a buck.) This case features two layers of protection and access to all ports, buttons, and features.
Note: The adhesive screen protector that often comes with this case is not included.