Electro-Pneumatic Regulator

[Alchemy99]

Hi all,
Im building a personal project, looking for a cheap regulator that can controll air pressure from 0-150PSI. i have a bunch of hand opperated ones, but i am looking for one that can take a control signal to set pressure.

i am building a device to aid in calibrating pneumatic testers. currently i have to turn the regualtor to a set point, wait for it to settle, and continue for every set point. trying to get as close to the set point as i can. (some units +/- .01 PSI, others 1PSI. from 0-150PSI) normaly every 5 or so PSI.

I dont mind having to build one, i just have no clue where to start. (stepper motor on top of a regulator with a Transducer attached to the output. is what i was hoping not to do)