I just wanted to report my experience with getting a custom nonsport iPhone case from a company called Smartish. The process was straight forward, it took only 10 days and the total cost was $34.99. The design studio can be found at:
You can use any non-copyrighted image. The printed result has a plastic texture and appears kind of "melted" onto the back the case. You can actually print on the entire back surface of the case. They work with a variety of iPhones and also Galaxy S. Hopefully it will be durable.
PS They are not paying me for this endorsement but I am willing to accept cash and gifts!