Many people here post un-productive comments and are very harsh but there's usually some truth being them. My advice to you is to take all the advice you "want" and build upon that. It takes a long time in order for you to get it "right" so keep changing things until it sticks.
Have you tried using Amazon as your search engine for ISBNs? From experience it is very accurate and complete. You can scrape using a URL like this: http://www.amazon.com/s/ref=nb_sb_noss?field-keywords=034551...