We present a decentralized market protocol for allocating tasks among agents that contend for scarce resources. Agents trade tasks and resources at prices determined by an auction protocol. We specify a simple set of bidding policies that, along with the auction mechanism, exhibits desirable convergence properties. The system always reaches quiescence. If the system reaches quiescence below the consumer's reserve price for the high level task, it will be in a solution state. If the system finds a solution it will reach quiescence in a solution state. Experimental evidence supports our conjecture that the system will converge to a solution when one exists and the consumer bids sufficiently high. We describe the system's application to and implementation in an agent-based digital library.