It depends. Generally after a newly released book has been through its hardcover run, and the market has settled on a paperback price, I would be willing to pay that; the paperback price for the e-book version if it is a title I wanted. This presupposes that I am getting a quality e-book version.

The story changes for older releases. Right now I wish I could find an e-book version of Johnny Tremain by Esther Forbes. If it was out there, in quality EPUB format, I would be willing to even pay a little bit more than the current price for a new paperback; $6.00 at Amazon.