In this paper, we propose an economics-based, distributed multicast scheme for wireless relay networks. Our goal is to construct efficient multicast routes that serve as many users as possible with the given bandwidth budget. The proposed scheme, called Price-Based Distributed Allocation (PBDA), allows each node to make decisions independently. Through analysis, we prove that the original problem is NP-complete, and show that our heuristic has polynomial-time complexity. We also conduct simulations to evaluate the scheme's performance. The results show that by utilizing relay nodes, PBDA can provide efficient and stable allocation of wireless resources. PBDA produces low-signaling overhead and can be deployed in a very efficient, high-performance manner.