Book Price Script - Comparisons and my price (using equation

I would like a price comparison script that compares the price of websites in which I am affiliated to (amazon, [login to view URL] etc.) in which a user can enter the ISBN of a book and find the best price for it- as well as my price (if I have it available.) Secondly, I am implementing a buyback program as well, which I will also search affiliates as well as my own buyback (based on an equation off of amazon prices). Notes would be helpful so I can later modify the equation etc. Furthermore, If possible I would be interested in later making pages with pre-inputed data (isbn's pre searched for course lists at the school that I attend.) This is my project aimed at a specific locale of universities. Please offer- I will accept reasonable requests of good quality scripts- may continue to hire for other projects. I would if possible like to own the rights to this script. Thank you, Daniel @ BookSlash Any format that works well works, unfortunately they only give me 5 options. The website is new and I can make modifications easily.