It is complicated for a number of reasons ,I only know of Multi-cam here in Melb and second hand 14 K there may be others working on a small scale .I was thinking about this the other day adding up the materials and sourcing the screws ,rails,bearing blocks ,spindle Inverter ,steppers and so on it was not bad but that was 400 mm screws which in reality gives maybe 300 travel or less .So I keep forgetting you have to add the carriage and so on my 1600mm screw gives 1380mm travel with my set up, then the machine gets large .Back on track I don't see too many second hand ones about either odd realy .