Peer-to-peer file systems are typically vulnerable to denial- of-service or free-loader problems. Those that address these issues employ approaches are either simplistic or require a centralized authority. In this paper, we explore how a zero- sum trading system can provide strong quotas to a peer- to-peer distributed file system without any centralized authority. We will treat each member of such a peer-to-peer system as an autonomous agent, interested in preserving its own disk storage. We develop a model for these agents, and present experimental simulation and external emulation results from a multi-agent reinforcement learning model demonstrating the validity of this approach.