An easier way of doing this sort of thing would be to advertise 'For Sale' or 'Wanted' items in your sig. People can PM you if interested, and it saves the hassle of making and maintaining an extra forum. Of course, any transactions would be at your own risk, but that's up to the people involved, and if advertising is done entirely on an individual basis, then EoFF can hardly be held responsible for any mishaps.
I don't think this sort of thing is disallowed under the forum rules anyway, but I might be wrong.