Presumably, though, those are also things that you'd need for a physical print book, and you could share some of that effort / cost between the two? Maybe this is a naive assumption, but I would assume that the total cost per unit of ebook is still a decent amount less than a print book, even when factoring for the publishing costs, purely due to the fact that you are dealing with a digital version compared with a print version that needs real materials and labor.
My question is, where do people buy epubs for these? Are you buying them off of Kindle or similar and stripping the DRM? My biggest withholding is that I can get used paper books for quite cheep (ie, from thriftbooks or similar), but there's not really a similar marketplace for digital versions (understandably so). Maybe I'm just cheap, but I have a hard time justifying near-full-price for books that I can get the physical version for much cheaper, or I already have sitting on my shelf at home.
I sit here typing on my DIY split keyboard powered by 2 nice!nanos. It's worth noting that a typical wireless split keyboard (separate left and right halves) uses 2 nice!nanos, so really it's only 25k people interested. That's assuming each person only builds one split keyboard, which... All the keyboard fans I know start with one, but don't stop there :p