I agree with Norm, this is what I've been looking into.
Unfortunately, some of them are *way* more expensive than they should be. Really bugs me.
So watch out for the ones that have immitation leather outsides - but then charge you like its real leather.
Another way to do it that is very cheap is what I do some times.
Get two pieces of foam core, put tissue paper between them and spring loaded clips to hold them together. Put the paper bewteen the tissue paper, put the whole thing inside the clipped phone core and you're done. Not very good looking, and kinda clunky. But it works.
Eric