Ask HN: Review our startup, fairbooks.com
We just launched our new startup, and were hoping for some feedback. It's a textbook buy-back company.
You might want to be careful with the word "guarantee" however -- I entered an example book (0312185480) and your price was $3 while the going used price on Amazon is $7.75 (plus a s&h allowance). I checked the faq for the guarantee details and didn't see anything.
I personally would switch to focusing on ease instead of price since selling books one at a time via Amazon is quite painful.
May be you would want to escape the characters in the input field or use better regex checking. (not allowing anything but ISBNs). I just googled for ISBN regex and there were many decent resources.
Also, many notable flaws with the design. The contact page/add book page/your info page overflows the base wrapper.