I have one of the M-Edge leather cases for my 505. I love it. It feels ... booky. The only problem is that now I need a case case to protect the leather! I stole my netbook's padded sleeve (the netbook has a sturdy case of its own anyway!) and I use that to protect the PRS when I'm putting it and its case into something where it might get damaged.
I'd trust anything from Case Logic. Probably 3/4 of my potentially breakable stuff is in their cases, and I've never had a problem. Something like
this case is what you're looking for.