Need to control the position of an Actutor

I need to know the least expensive way to control the position of an actuator, either linear or rotary. For exmple, I need a knob (probably a potentiometer) mounted on a panel and hardwired. If the range of the knob is 0-100, when the knob is at 0, and using a linear actuator, the actuator would be fully retracted, and with the knob at 100 the actuator would be fully extended. Likewise if the knob is at 50 the actuator would be at its half way point. This would all be at a very small scale. Actuator = 25-30mm stroke. Not much room for a lot of extra electronics. I would prefer off the shelf, but I can build if necessary. Thanks for any help.
You could start with an actuator designed to be controlled by a potentiometer.

Honeywell's Series 90 Modutrol partial turn rotary motor/acutators are controlled by a 135 Ohm pot.

Of course, the challenge will be whether the actuator
- fits and mounts
- is fast or slow enough
- has enough torque

135 Ohm control.JPG