EN
Relation of price and quality is the base on which the seller and buyer base their decision. Perspective of transaction costs shows the individual transactions in other relationships than the supply-demand. This article presents one of the models of game theory "prisoner's dilemma", which clearly shows the importance of information in commercial transactions. Lack of trust leads to inefficiency, what causes smaller benefit of both sides of the contract. Choosing the dominant strategy, they reach as a maximum the Nash equilibrium. The problem grows in case of the chain of the transaction, because individual links driving the opportunism and the experience deepen the inclination to the dominant strategy. The buyer must look for information about the product, which together with the price is the base of his decision. Therefore, he is exposed to the negative effects of information asymmetry. This can lead to the significant loss, as shown in the model.