Barter
The Barter screen allows you to trade items securely with other players, unlike the Trade screens which are just one way methods of giving items to players the Barter screens allow you to enter how much money you wish to receive for the Items your trading.

The Player you are trading with then can accept or refuse the trade via the Barter Status window, if the trade is accepted then the items will be given to the other player and you will be given the money you wanted from the other players held funds.