Because I just bought one! :-) Secondhand Chinese 6040 that's apparently got all the kinks worked out and has new good PSUs, a miniITX PC included with Mach3 and an enclosure with all the electronics / drivers / buttons / screen etc.
It's at the other end of the country but being put on a pallet shortly I hope. I expect to get it sometime next week and then the real learning curve starts!
Cheers - N