Check sleeves and cases sold for netbooks. A quick look at the one that came with my ASUS EeePC 901 makes me think it would fit your specs. It's too big for my 505 with an M-Edge Executive cover, though -- an inch or so too long.
I've seen some of M-Edge's Kindle covers recommended, and also Case Logic might have something that fits. Book Armor cases fit the standard cover, but I don't think they fit the lighted one -- but maybe they do; it can't hurt to look.