I think it could be a good idea to add a section in the For Sale section for members to leave feedback about things they have bought from fellow members.. even just a comment to say wheather the sale went OK or not...

EG. Bought XXXX item from <username> had no problems.. would deal with again.

I feel this could be of use to a lot of users.. especially new users who may find a member has something that they need for sale.

Good idea

Im not to sure as I think it will add more clutter to the site. How many people actually sell stuff on the site as I feel the majority is just links to eBay?

Perhaps a comment in the same thread commenting on the sale would do?