Well I've been lurking around here for a while and probably should contribute for a change. I haven't put a screen protector on my reader but this company can cut them to fit for a reasonable price:
http://www.photodon.com/lcdprotect-sheet.htm
I ordered a custom sheet for my laptop and it arrived quickly and was exactly as ordered. My only regret is not asking for the scraps as they had to cut an existing sheet down. They would have been great for camera LCDs, etc.