I think people often assume that just because something is in digital format, and not in print, that that should slash the price drastically. That really is not the case, though. When you buy a book, you are paying mainly for the content, not the medium. That content is the same whether the book is in digital format or in print format, and to produce that content they have to pay copy editors, illustrators, and who knows what other kinds of staff. As another example--and one I'm familiar with because I work on a magazine staff--consider the publication of an issue of a magazine. Whether the articles find their way to the newsstand or the web site, the production process used is the same: Layout, editing, fact-checking, and input must occur no matter what.