Amazon Price Comparisons

Bookseller needs simple program to download and compare price, condition and sales rank data for all books listed on [login to view URL] and Amazon.ca. Several book scouting services already have arrangements? with Amazon using Amazon Web Services to download their complete databases to allow book scouting subscribers to? compare the? sales ranking? and sales prices of particular books. I need a program that downloads and compares both databases with variable parameters (eg. sales ranks, differentials between cost for? "New" and "Very Good" on each web site i.e. [login to view URL] and [login to view URL])