Still loving my PRS T1 and I've been using a carry case for quite a while until my sister stumbled on Sunsky-online.com and told me to check out their Reader cases.
They are similar in style to the official Sony ones, and can be used as an alternative if you're not willing to pay the fairly high price. The quality is okay (it was only 12 bucks including shipping) and shipping does take quite a while.
The cover is thin and the reader fits well! I purchased the red version but they also sell black and white