Since I already build and sell ATC upgrade and DIY kits, most with a fixed rack are (to me) mechanically simple, what do you consider to be low cost?
I've seen and appreciate what you make and sell. I've been contemplating this ATC challenge a few years now and ideally want a solution that doesn't require pressurized air (no compressor in the room where my CNC sits). I want it to retrofit into the frame of my Probotix meteor, leaving the front edge/rail rather than the back edge/rail as the best location for picking up a new tool. The machine also homes at the front left corner, so a tool rack would have to slide in and out of the accessible area. That implies another stepper/servo for the sliding, which of course needs another signal from the controller.
I've already figured out a post processor, the subroutines needed when a new tool is requested, a tool rack, and how to drop off and pick up and power entire trim routers as the spindle. Each trim router is $69. Not expensive, but not my ideal spindle either. Moving the tool rack in and out has me "stuck" at the moment.
If a complete 25" x 50" CNC with no ATC can be had for $4300 from probotix, I'd want the ATC 4-tool option to keep the total price under $5000. Where I work any purchase under/equal to 5K doesn't have to go out for bids. A practical cost, but I realize not necessarily a reasonable cost for the technology.