We specify and evaluate a protocol for cooperative relay communications in wireless networks targeted for low-budget and energy-constrained off-the-shelf hardware. The protocol located at the Medium Access Control (MAC) layer integrates radio resource reservation, relay selection, and packet flow. Performance is evaluated with different parameters, such as node density, channel coherence time, and data packet size. Higher network-wide reliability and throughput compared to non-cooperative protocols can be achieved in dense networks and unreliable channels. At the same time, throughput does not degrade in sparse networks or good channel conditions.