Feedback plugin

Hi !

I"m looking for a feedback plugin for Marketpress. I saw that it's possible to allow comments on products page, so it's easy to build something to rate products. But I'm searching something more developed : I want a solution to make feedback only for people who buy something. Is there a solution to do that ?

I saw this topic who talk about a good solution, but I don't find this plugin on the Internet. Maybe someone can help me for that or is it possible to have an adress for contact cstevenson ?