There are tens of thousands of books that can be yours to use by way of public domain. Have you heard about public domain? There are public domain books that are available and you can go ahead and use them for commercial purpose only after adding value/content to them. Once the copyright expires then the book becomes available in the public domain. It's totally legal to resell such books and gain profits.
Most of these books are downloaded as txt.files. You won't need to convert the files and this is a lot easier than creating a new ebook in the pdf format. You could also create your own audio books for sale from the public domain book.
You can, of course, register a good domain name and thereafter build your own website to advertise and sell these books. If you don’t want to build your own website then you can sell them on eBay.
These ideas come from Alex Mandossian blog and Armand Morin. They talked about these ideas, and others, in their Big Seminar and preview teleconference call. I felt that these were such moneymakers, with lots of potential. There is a large market for it, so you should take advantage of these ideas.
What information do you know about public domain books?