You would have to do it by screen scraping: Write a program that makes the HTTP request to search for the book in question, then parse the HTML response and determine what the result it.

Additionally, use the ?layout=compact option on a the wishlist URL (http://www.amazon.com/registry/wishlist/?layout=compact) to simplify the HTML served by Amazon. The script would then want to extract the Amazon Standard Identification Number (ASIN) from the linked URL. For example, B007X5ZBU4 is the ASIN for "The Launch Pad: Inside Y Combinator, Silicon Valley's Most Exclusive Schoolfor Startups [Kindle Edition]" (http://www.amazon.com/The-Launch-Pad-Combinator-ebook/dp/B00...). Now take the list of ASINs and convert them to ISBNs. I'm sure there's an Amazon API that can handle this lookup. With a list of ISBNs you can search against your school's database of books. Depending on how open they are with this information there may be an API that allows you to search by ISBN. Maybe talk to a tech-savvy librarian at your school.