You might want to look at the BooKArmor case from OmniScience. I had one for my prs-505 and have one for the PRS-950 coming in the mail to me. Very lightweight, super strong, and offers incredible device and screen protection!
http://www.amazon.com/BookArmor-Trav.../dp/B002QKGMO0
more details
http://www.extremeinkjet.com/BookArm...okarmor650.htm