Oh interesting, I'll take a second look. Whatever Amazon API I checked was only returning pixelated thumbs. Good luck with the product. Next up is "How I made a million bucks reselling books" blog post ;)
If you have an active Affiliates account with Amazon, and you qualify for the API access, it won't be enabled even when you get your key-pair. The API will throw a generic error "Too many requests."
You have to go to >Contact Us< section of the affiliate program and ask them to enable your access.