how hard would it be to take a standard off-the-shelf printer and replace its controller board?
it's not like you can put DRM on a motor. and let's be honest, sourcing the parts for a printer is the real hard part. programming it/figuring out how to drive it is hard, sure, but it's just firmware, anyone can download it off the internet.
you wouldn't buy printer parts. but you can buy a microcontroller and download firmware.