Dastrdly, I just thought of something.

Find a high speed machine manufacturer or robotic assembly machine manufacturer in your area. Then try to contact their electrical controls engineers. They may have a ton of samples laying around that might work for what you want to do. And, they may not charge you for them. Then all you need to do is find someone to do the mechanical mods.
I know before I retired I had several full systems in my office that I would have been open to donating for such a project. Heck I might have even given a hand designing and programming the controls.
Edit: Another way would be hydraulics with linear position encoders. But, the noise of the pump might be a problem. And, heaven forbid if you sprung a leak in one of the hoses or valves.