i could go on with a long post, but i'll just say that to see this implemented is a beautiful elegant solution.
Also you speak about "sell at market" and if they institute that then on the buying and selling end would they implement limit orders? for example the options may look like
Sell 200 scrap
-- Limit--- amount 5g/scrap
order open for 24hours
this may be too advanced but just intellectually the next step