@Edent
I don't feel e-readers are all that expensive; I don't think that's the main reason their impact has been limited.

I think it's mostly the walled garden aspect of books. You really can't get a book "wherever you buy books", but are locked into a silo. Kobo is better than kindle in that respect but that's still damning with faint praise. I can't give a book to my wife or a friend when I'm done with it. I certainly can't buy a second hand copy.