A friend and I were discussing this recently, and he came up with a good idea.
What he suggested might be impossible to implement, but why not have a location, for example Fair Trade, that when you enter a chat interface appears with items for sale. Or it could also be a Trade Booth, something like the Grid. Digital Trade! With respect to the interface it could be akin to a stock market billboard - but Rubi-Ka style. And what would be nice is a the shop price included with items by default (avoids having to run shop to shop to have an idea of item value).
Chat could remain as it is, without all the trade channels cluttering communication. You guys are talking about adding more windows?! ugghh...