Model-based testing has been successfully applied to conformance testing of reactive systems such as network protocols, both on general purpose and embedded systems. However, doubts persist about the overhead on time and human resources required. This work addresses the empirical quantification of model-based validation costs for medium and small sized projects. In particular, it asseses the cost of model-based testing for cross-layer protocols. This paper presents how, in spite of some initial constraints in budget, human resources, time frame and available tools, it was possible to produce a formal specification or model, implement a fully functional prototype and test it for conformance with test cases derived from the model