A cognitive radio network where an incumbent primary operator and an entrant secondary operator compete for users is modeled using queueing and game theory. The economic viability of supporting the secondary operator service using an opportunistic access to the spectrum owned by the primary operator is assessed. Against the benchmark of the primary operator operating as a monopolist, we show that the entry of the secondary operator is desirable from an efficiency perspective, since the carried traffic increases. Additionally, for a range of parameter values, a lump sum payment can be designed so that the incumbent operator has an incentive to let the secondary operator enter. Additionally, the opportunistic access setting has been compared against a leasing-based alternative, and we have concluded that the former outperforms the latter in terms of efficiency and incentive.