The ATC has several components that aren't actually re-brands of offshore contractor parts, but actually designed-by-Tormach (or their design company which I think is pretty tightly integrated.)
That team doesn't sell their parts separately, so you can't find an "off label" version of the Tormach ATC, as far as I've been able to determine.
What you can do (and people have done,) is either build your own from scratch (which will take forever and cost more than just buying it,) or get something like a low-cost robot arm, and re-write the tool change macros to control that, and the appropriate solenoids for the draw-bar. Neither of these are of course cheap-and-easy -- if you want an ATC with the lowest actual outlay in dollars and time, the Tormach solution is likely the best chance you have.