Cognitive radio technology has been proposed to improve the spectrum utilization by sharing the frequency spectrum bands between the licensed and unlicensed users which are called primary users (PUs) and secondary users (SUs) respectively. The main objective of the SUs is to achieve their QoS by exploiting the unused spectrum while the PUs aim to get high profit by leasing their unused spectrum. Pricing and transmission power are two key issues of interest to PUs and SUs as well. In this paper, we propose a power pricing model wherein the PUs attain some revenue by renting their unused frequency to SUs that use suitable power levels to transmit which do not interfere with other users in the network. In our proposed model the SUs coexist with PUs in the same network where they can transmit over the same channel simultaneously. Performance evaluation of the proposed model demonstrates that the scheme helps in using the frequency spectrum more efficiently and increasing the gained profit of the PUs in comparison with the other existing models.