The Market is a place for merchants, farmers ,miners and other people to buy and sell.
The Market is open for customers only in the District where its located and the adjacent counties. (e.g. the market in Minas Tirith is open for people from Harlond, Parth Pelennor,Western Osgiliath and Thinbar , but not for those from Sindbar, Morgai or elsewhere.)
The owner of the Market may charge a price for people who want to sell their goods. however, to sell at a Market you need to be located in th very same district the market is in.
The government of the realm or the Warden may charge taxes on traded goods.