I won't pay more for an ebook. The bottom line for me is that the ebook is worth less. Disregarding publishers' costs, or "value pricing," etc, the ebook delivers less overall value.
I'm not talking about nebulous notions of "feel" or "smell," etc. I like paper books well enough, and probably still read more dead tree than I do electrons, but the "romantic" aspects aren't very important, and for some situations the ebook is the better experience.
So it's not to say that the ebook delivers no value, or that in some respects it doesn't deliver superior value, overall it's still less. Illustrations are less useful, including covers. Ebooks are more linear, less random access -- it's like going back to scrolls after a lifetime of codices.
But most importantly, it has no residual value when I'm done with it. I can't lend it or sell it or give it away. It can't be passed around between all my friends (yeah, even if it comes back a ragged shade of its former self...) I am a re-reader, so most of the time I don't get rid of books permanently, but ebooks remove the choice.
This is true even if it is non-DRMed in the first place. Selling is out of the question, and giving or lending, although possible, is a bit morally questionable. (I'd make exception for Baen books, since they seem to be in favor of such lending.) Even disregarding any of that though, it's a lot less convenient.
So for any given book, the ebook price will have to be less than the paperback or I won't buy it.