RE:There could also be the possibility that----I don't know about where this hign construction cost of building these units idea came from. I believe the major cost of a unit would be the housing for the components and the portable cart arrangement that it rides on. Apparently the components can be had at a Radio Shack kinda place (electronic supply) for low costs in that area. Mind you,..........., If you were to build 5000 of them.......