Nekokami's idea of providing an ecopy of the book with the sale of the paper version, could be implemented in an easy way. This copy could be on a fragile magnetic strip or an RFID tag, taped inside the book. Any attempt to remove it will destroy it. A scanner, proprietary to an author's guild, would bring revenue by it's sale. The funds generated, plus an extra at the sale of the book, would suffice to provide the e-book without DRM.
