Allot of co2 controllers that run more than the co2 still require a electric regulator that actually controls the on and off of the gas, just a FYI.
What else do you need to do, exhaust fans, light timers, Humidity. They have units that do it all, well almost everything. Give us a list of functions you want it to do.
I have never used one in my grows but have looked into it a lot also held a lot of them. even for the lower end, ,which is still sick, that will do temp, co2 power outlet, humidity, and maybe light timer,they're 600-700 for the low end. I would love to have one. But once you get the ball rolling not to many things change.
You can get a few smaller units and have good results, I only use 2 timers, one runs lights and hood vent, and other is for co2 (electric valve was 120 USD). I found a $35 adjustable Thermostat to run my exhaust fan. Works for me.......but I am in soil right now, aero is calling me, I want faster growth, soil is killing me, especially seeing how fast hydro/aero grows, time to make a switch I think