Pricing a book for free on other outlets is a very common trick writers use to give their books away for free on Amazon because of Amazon's price matching policy. What writers need to remember is that the process is automated; it is a robot, a program, which makes the decisions. So if you have a book on Amazon make sure any promotional excerpts you publish elsewhere at a lower price are very obviously different from your Amazon book. Lest you confuse Amazon's pricing bot!
Please check out my first collection of short stories, The Sun Zebra.