This is something we will add. Working on the parameters now. Something like the seller will be allowed with each listing to hit a button which he can then enter the buyers username and request feedback. It would only allow one request per item posted for sale. The buyer would be able to rate postive, neutral, negative and leave a short comment.

Under the users name, location, avatar where posting we could have the summary feedback rating and you could click on it for more detail about it. More to plan on this before programming it as it can be a little complex so I want the foundation to be solid.