Amazon.com has a Pre-Order Price Guarantee.
If the price of a pre-ordered (ordered before it is published) book goes down between the time you order it and when they ship it, they give you the lower price. This happened on my order and they did, indeed, give me the lower price. I saved $0.15 in this manner.
If the price of the pre-ordered book goes down after they ship and charge you for it, they will refund the difference in price. This happened on the same order, and they are giving me the lower price, again. The price of the book went down another $0.15. In the end, they lowered the price on my book twice, for a total savings of $0.30.
I’m getting a $0.15 refund on my credit card for a book that is on its way to me, as I write. No, I don’t know how much the processing costs are for a refund; both Amazon.com and my credit card company have to update their records.
I’ll take the refund. I just don’t know where to spend it.