Markets are the main hubs of SAELIG. All resources flow through them and they act as gathering points for all kinds of people. Most maps have multiple markets which along with the travelling merchants help build a dynamic flowing economy. No item simply exists, all items that flow through the market were created by a character.
Market prices are based on supply of each item and thus money can be made by buying in one market and selling for more in another. This strategy can be hard to master because the AI are also always on the lookout for a good deal as well.