Device-to-device (D2D) relay enhances the capacity of a mobile network. If the channel quality of a user equipment (UE) is bad, the UE asks a neighbor to get its data from the base station and forward the data to it by using D2D communication. Since cellular and D2D communication can share spectrum resources, the spectral efficiency will rise. As UEs are owned by self-interested users, they may not provide relay services gratis. Thus, some incentive methods let UEs exchange tokens to buy and sell relay services. However, they assume that each relay service is worth one token and offers a fixed data rate, which lacks flexibility. Through the law of supply and demand, this paper proposes an economy aware token-based incentive (EAT-BI) strategy. A supplier (i.e., the service provider) charges different prices for its relay service with different rates. A consumer (i.e., the service requestor) takes different policies to choose a supplier based on its tokens and may bargain with suppliers to avoid starvation. Simulation results show that EAT-BI can efficiently promote D2D relay use and increase throughput under different mobility models of UEs.