Congestion control is an important research area in computer networks. Using PROMELA/SPIN, we verified that priority pricing schemes can be used to effectively control congestion. Under the simulation/verification framework provided by SPIN, we verified the propositions that the enforcement of priority pricing on a network link (i) results in an equilibrium state in packet allocation, and (ii) effectively controls congestion level when pricing is being dynamically adjusted. Furthermore, we have extended these propositions to demonstrate the convergence property of equilibrium in packet allocation. This particular result would be difficult to verify with existing network analysis tools.