Market is one of the places where all three main player roles interact in the game. Market mechanics are implemented for players to be able to distribute their produce all around the world. It gives all types of players a partial freedom from the burden of doing everything by themselves, since they can buy the needed products made by others.
Businessmen buy resources and materials required for production and construction, security systems and other products required for insuring their safety and day to day operations, or sell of their own produced goods.
Scientists buys food for restoring their energy, medical consumables to keeping themselves healthy, and gear for protecting themselves from other player attacks, or sell created security systems.
Warriors buy gear to protect themselves from open world attacks, and ensure their ability to do security related jobs. They also buy food and medicinal supplies to keep themselves healthy and full of energy.
The price seen in the market will differ for seller and buyer, because of the different taxes applied to the buying and selling processes, may it be sales, import or export tax.