[lukevdp]

The first step would be to validate the opinion that people prefer to see the books they read. Then you would need to find out how much people are willing to pay for it.

My guess is not much, because people can just buy the book if they want it. Also keep in mind, the cost of an ereader is around $80-90 - quite an expensive cost to add per book.

[cstross]

Entry level price for an e-ink device in the UK is now down to £35, i.e. US $55-60, of which 20% is VAT (tax); in the USA it's down to under $50 (in some cases $35 with a mail-in rebate). Furthermore, this is the retail price for the reader. Unless they're heavily subsidized to below cost price, the device itself is even cheaper.

[Elho]

I would only use the e-ink technology. All other features wont be necessary. So really the most simple version of an e-reader will do.