My educational websites(for now just a blog and squidoo lenses-this summer a more extensive website) are already getting pretty good search engine traffic. Of those I am getting 6-8 searchers a day looking for math worksheets(I expect this number to go up as I cover more topics). Anyway, my main goal is to provide the best free secondary math websites on the internet and thus I am looking for other ways to monetize my sites. I was thinking of putting together books of worksheets and selling them to teachers. I only want the site to be free for students so I don't mind selling things to teachers. Creating the content won't be a problem, but I was wondering what is the best way to handle the publishing and transactional part of selling an ebook?

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