The primary trouble with e-books, as I see it, is range, not device or price. Because publishers are so fearful that e-books will compromise "real" sales, they just don't offer most books electronically. That doesn't prevent them from being available electronically, though. It just prevents the publishers from being paid for electronic versions.
The second problem is that you can't even express interest in them without being treated like a criminal. The fear, again, leads publishers to demand DRM on what books they do offer. In most cases, the restrictions are so tight that you'll probably lose access to the book after you read it once.
Now, along with the iPad, Apple is trying their hand at e-book sales. I doubt apple's iBookStore will solve either the problem of range or open access, let alone price.
Mokalus of Borg
PS - Apparently in some cases the iBookStore charges more than for a physical book.
PPS - That's because publishers set the prices, and they don't really want you buying books this way.