Did you know that if you buy a Kindle book and don't like it you can return it and get a refund? You've got 7 days to change your mind (I think).
I've probably bought more books since discovering this - well hidden? - feature because my risk of purchase has reduced enormously.
This didn't work for 1 book and I suspect it's because I bought a sample of the book a long time ago, then bought the book last week, and - for some reason - that disqualifies me from a refund. Don't know.
So, how do you get a refund?
(From amazon's help):
Returning Kindle Books
Books you purchase from the Kindle Store are eligible for return and refund if we receive your request within 7 days of the date of purchase. Once a refund is issued, you will no longer have access to the book.
To request a refund and return, visit the Manage Your Kindle page. Click the Actions tab for the title you'd like to return, and select "Return for refund".