Nook replacement?

I've somehow damaged the screen of my Nook Simpletouch. It's not too bad at present, just a blotch a couple of letters wide and high near the bottom of the page, but it's a bit annoying and I'm worried it might get worse. It's not urgent, but I think I'll replace it if I can find a cheap substitute - but it must be an e-ink based ebook reader, not anything with an LCD screen, the power life is too limited on anything like that.

I get the impression that this technology has to a large extent been sidelined by cheap android tablets etc., but if possible I'd like something a bit faster than the Nook and easier to organize - you can't organize books into "shelves" from the computer with Nooks - and Calibre compatible.

Any suggestions?