The Economics system in Star Citizen is very dynamic, players actions effect the supply and demand of goods produced and subsequently the prices.
In order to create a fairly stable economy, and yet one that is still able to be affected by player actions, the economy in Star Citizen is built to represent millions of entities (whether players or NPCs) that work together to move resources and finished goods from one end of the galaxy to the other. Miners and other resource gatherers work to extract basic resources from the available supply, traders collect those goods and deliver them to other places, escorts protect those convoys from harm (while pirates attempt the opposite), refineries turn the raw goods into processed goods, and factories collect these processed goods to build the finished products that are in demand on worlds throughout the Star Citizen universe. These goods are not assigned an arbitrary fixed price at each location. Instead, we are creating an organic system that keeps track of how much of everything is available, how much it is needed, where it is needed, and what individuals are willing to pay to get it.
Because the simulation reflects a real population going about their business, if a player is not available to carry ore from Ellis to Terra, an NPC cargo hauler will step in and run the route. If escorts are needed, and players are unavailable to escort that transport, then NPC pilots will escort the vessel. Pirates, too, might be NPC or player ships.
Meanwhile, the nodes that are producing, refining, and consuming these goods are run by non-player characters, as well. As players progress in the game, they may choose to purchase some of these facilities and take over the day-to-day oversight.
Business goes on, and players step in wherever they wish to take part.