Cognitive radio (CR) provides the platform for dynamic spectrum sensing, spectrum allocation and intuitive decision making in a very rigid spectrum framework architecture.Accessing white spaces in licensed spectrum through spectrum hopping and managing interference in free-to-use spectrum are means by which CR can help improve the overall spectrum efficiency. But utilizing these spectrum resources generally comes at a price, whether that be a monetary cost or interference to transmission. Resource-sharing therefore demands a two-way exchange for users to effectively transmit simultaneously across any spectrum. We investigate how this cost changes given the application of CRs in a commercial or military setting.With commercial or licensed spectrum, monetary incentives are important, and therefore spectrum leasing or spectrum trading is often sought as the avenue for resourcesharing. While the bulk of spectrum sharing research focuses on interference mitigation or rate maximization for the cognitive or secondary users (SU), the work in this Thesis deals with incentivizing the licensed or primary users (PU) that lease out their spectrum.The resource-sharing protocol incorporates three opportunities for spectrum exchange in the form of spectrum access, spectrum sharing and relaying, that each have a marketdriven cost. With the highest SU bid gaining transmission rights to the leased PU spectrum, this model perfectly showcases the demand-and-supply economics involved in a commercial setting.