absolutely brilliant idea... the only clarification I would want to see is a expiry time system on item requests... Someone puts up a request for an item and a price they're willing to pay... money goes into escrow (on the system) until someone either fulfills the order or a certain period of time elapses. If the order is not filled the money gets sent back to the user via the /mailbox system. If an order is accepted it is locked out for a period of 24 hours so no one else can accept it as well... if the order then goes unfilled for that 24 hours it is opened up to everyone else again and the person that had the original hold on the order would have to take the order again.

Just to prevent a potential scenario where a single user could lock out the bid indefinitely I would suggest that if an order goes unfilled, the order can not be retaken by the same user account (pol account, not character) for a further 12 hours. perhaps even a system where a single character could not take more than a certain number of orders in a set amount of time. who knows... this idea has so many possibilities to control it effectively it's hard to delineate all of them. times can of course be juggled and balanced around as needed, but I like where this idea is heading and would absolutely love to see a system like this in game!!