Open-Mesh type equipment bought in bulk maybe? »
www.open-mesh.com$2 per month does seem low even if Open-Mesh type equipment is used. 500 devices, a worst case scenario I can think of, would be about $35,000. That would be about $6/month just for the equipment to be paid back in 12 months with no interest. Optimistically assuming a 4 apartment per one AP solution gets to $1.50 per month on hardware alone. See if they will give references to previous clients with you pretending to be a potential customer or will detail out examples of successful deployments in similar scenarios. It would not surprise me if you find out that the $2/month is just the starting point for most of their deployments and that the actual final cost for a successful deployment is much higher. If the buildings have no metal water or sewage pipes, are made only out of thin wood, sheet rock, and plaster, and have apartments less than 500 square feet, you get the $2/month service with a 12 apartment to 1 AP solution
Anything else and the cost goes up I bet.