Here's the response I got from Amazon when I asked about price adjustments:
Q: I was wondering if you offer price adjustments - for example, if I
buy something and the price goes down in the next month, would you
adjust the price?
A: Thanks for writing to Amazon.com.
I apologize for any misunderstanding.
as you may know, the price and availability of items at Amazon.com
are subject to change. Some discounts are particular to the time
that an item is a featured selection on our site; these discounts
are limited-time offers.
As the discount we are able to offer for any item is dependent upon
its availability, Amazon.com's price will necessarily change on
occasion. We are unable to honor a price that was advertised before
you placed your order.
Also, there may be times when Amazon.com runs out of stock of an
item that is also offered by one of our partner merchants. You may
see it displayed on our web site as available, but from a different
merchant and with a different price than you saw previously. Our
merchants set their own prices.
I hope you will be able to take advantage of the many discounts we
offer on your next visit to our store. We sincerely appreciate your
business, and we look forward to seeing you again.
Further, if you see that the price of the item you purchased within
30 days have gone down, we will honor the discount price and issue
you a refund only if your order is shipped within 30 days.
If you have further questions, please visit our online Help pages
Now, I really think my q was pretty straighforward. The answer not so much. I had made no inquiry about out of stock items for example.