BookSearch.app
 
Have you ever been at Barnes and Noble or Borders and wondered if you could find the same book you wanted cheaper online?  We at campusbooks4less.com have the solution.  Booksearch.app allows iPhone users to search for online prices of books given an ISBN number, even enabling them to purchase the book from an online retailer on their iPhone!
This application is also available as a native application at the iTunes App store (links opens iTunes).
 
Direct application link: Booksearch.app