As long as it's a deal between two members and the site takes no responsibility for the trade, the site has no legal responsibility for it. It might be a good idea to state that all trades are at the participants' risk, i.e. the site offers no warranty, express or implied, for the goods or tender of either party.
Anything beyond that is just admins' preference, but it would definitely be a good idea to get Hammerfel's input before starting something like that... though apparently he makes himself very scarce. Strange way to run a website.
