Get a barcode scanner, scan the ISBN and use that to do a API query on Amazon to retrieve title, author, category, price, etc. Store this info in a DB. Some scenarios: 1. Generally lookup should return something. Store these book by categories, e.g. business, children, fiction, etc. in their shelves/containers for physical browsing by your customers. The more subcategories you can do the better. 2. If price is bigger…
I've been using Tellico (http://tellico-project.org/) and a barcode scanner for many years and it works well. That's just for about 3,000-4,000 books, though. One of the other lookup options works. (ISBNSearch.org?)