This article discusses the design of the 2007 "Supply Chain Management - Procurement Challenge" (SCM-PC), a competition designed by the first three authors to evaluate the performance of mixed procurement strategies. Specifically, the SCM-PC Challenge revolves around a PC assembly scenario, where trading agents developed by different teams compete for components required to assemble different types of PCs. The Challenge requires the agents to manage supply chain risk through combinations of long-term, quantity-flexible procurement contracts and one-off procurement contracts for different components. Collectively the authors represent the top three entries in the 2007 Procurement Challenge. They present the strategies their teams developed for the competition, compare their performances, and discuss lessons learned from the competition.