I think what Sakrysta is saying, if I am understanding correctly, is that she doesn't see why there isn't a larger difference.
As an amateur writer who hope to get published one day, I fully understand everyone wants to get paid. But with an E-Book, you don't actually have to print the book. And as far as I know (which I admit probably isn't very far at all) the actual printing of the book on paper is a large chunk of the cost that isn't there with an electronic copy.
EDIT: And I see others have already replied before me saying otherwise, so never mind