Wanted to know if there was any documentation or plugins that allowed a site to pull prices and other information from Amazon.com on DVD's and other products. I'm creating a plugin that stores information about DVD releases and I would like to create code that pulls the price from Amazon, and calculates the difference compared the MSRP and of course provide a link to the Amazon page for purchase. I do know that much of Amazon's API revolves around the product's Amazon ID number, so I know I'll have to story it with the custom post type associated with the release. Has this been done before?
You're looking for something a little more advanced than a simple affiliate integration. Unfortunately, I don't thing there's an existing plug-in solution for the kind of interaction you're trying to achieve. That said, it should still be possible.
A cursory search turned up Amazon's Product Advertising API, which seems to be exactly what you'll need. It provides directly programmatic access to the Amazon product database, meaning you can find (and cache) product information and prices fairly easily.
You can use this to power a local search of the Amazon database for products or just retrieve information specific to a product based on a known Amazon ID. It's up to you, and I encourage you read through the documentation and see if this is the right platform.
I looked into this myself. The problem with Amazon's Affiliate API is that terms of usage state that it can only be used to actually refer customers to Amazon to make the purchase. You aren't allowed to use it to update your own prices to match Amazon's. The only way around this is to write a script that scrapes Amazon's site and looks for Amazon as the seller for whatever item.
See http://wordpress.org/extend/plugins/search.php?q=amazon&sort= for different plugins.
Sounds like you're talking about being an amazon affilate?