They sent me out a replacement back cover, no questions asked (I had an "issue" with mine). Excelent customer service IMO.
I wouldn't expect the back cover to cost very much if they do sell it seperately.
I told the person I was chatting with to tell their R&D department to make a case so we can all buy it. I was told they will pass it on (but who knows).
Maybe they have had a large enough demand for it and have decided to make a case? Time will tell.
"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." --Albert Einstein
and Google Code
for my sources.