One other concern : If someone buys a book, you digitalize it and destroy it in the process. Now if someone else order the same book a week later, do you digitalize it again or do you detect it's already been digitalized before and send the previous version. The latter seems more efficient (but maybe not legal?) but the former kind of allow you to keep/resell the version bought previously (which must not be legal from what I understood on your FAQ?).
