Purchasing an Open places the item on the market. If the user wishes to leave the market, he must make a sale and indicate it as a Close. It is only then that the item disappears from the market. If he was to make a sale without indicating it to be a Close, he would have two open items on the market (with the corresponding risk). He would then have to deal with both according to the contracts.

At present, you can only process charges, commissions and taxes as other flows.