https://bookfunnel.com/

Do I use it? Yes. Regularly

Cost: Mid-List $100/year

BookFunnel is a platform for building up or selling books in group promotions. Signing on to one of the group promotions with ten to thirty other authors, you are obligated to promote the promotion at least once in some manner over the course of the promotion. In exchange for an electronic copy of your book, you get the reader’s email address. BookFunnel is very adept at supplying your book to any electronic reading platform. And you get a broad audience of people who have actually downloaded your book. BookFunnel is also great at communicating and solving problems.