I have developed a tool that lists the valuation price for domains from Godaddy. The differnce it lists similar domain sale prices and the year they were sold as well, which the regular godaddy valuation tool leaves out for some reason.. Try it out. namevalu (dot) com
I don't mean to be a kill joy, but you've essentially made a mod out of a piece of GoDaddy software. If your site scales / had mass appeal, pretty sure they'd sue. IMO