Thom Wetzel sent me information about his new site, the Wishlist Buddy.
As Thom notes:
I've noticed that a lot of the times with books, DVDs and video games, the prices usually start out high and work their way down to less than half price over time. I used to add items to my Amazon Wish List and wait for the prices to drop, but one day I realized "why not make a site to do it for me?" and that's how Wishlist Buddy came into existence.
It is easy to get started. First you create an Amazon Wish List with the items that you would like to purchase. Then you create a Wishlist Buddy account and associate it with your list. Finally, you attach a "target price" to each item in the list. From that point forward, you will receive an email each time an item on your list reaches the price that you are willing to pay.