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Recently overlay/underlay framework in Cognitive Radio (CR) have been studied and demonstrated the benefits such as spectrum efficiency and channel capacity maximization. We assume Secondary Users (SUs) can choose to either acquire a dedicated spectrum with constant payment or to use a Primary User (PU) band for free. However, using PU band yields delayed transmission cost. In this paper, we apply M/M/1 queueing model with heterogeneous service rate to derive the explicit expressions for the expected delays of an arbitrary SU data packets. Based on this, the SUs need to decide whether to use the Primary User (PU) band or to acquire the dedicated band. The interaction between selfish SUs is modeled as a noncooperative game. We prove the existence and uniqueness of a symmetric Nash equilibrium, and characterize the equilibrium behavior explicitly. Then an appropriate price of the dedicated band can be defined. Numerical analysis are used to prove a high degree of accuracy for the derived expressions.