Ranco has a dual stage. The one I looked at cost $150 from Morebeer (probably not the lowest price out there...) That was for a wired model.
Yes, the STC-1000 needs to be wired, but that might cost $10 to buy the box and outlet(s). Personally I have a TON of computer cables, so other than the receptacle end, I didn't have to buy the wiring.
They are not terribly challenging to wire if you take it one step at a time, and of course if you are wiring a simple single outlet version it's pretty easy, and if you do as some people have done and wired whole outlets for Heat and full outlets for Cool, and another outlet for constant supply, it gets slightly more tricky, but I think it's nothing the common man couldn't do with a pair of wire cutters, a small screwdriver, and a pair of needlenose pliers.
I ended up cutting the shape of an outlet directly into a waterproof electrical project box on a CNC mill at work. There are ways to not have to do this, but since I had the machine there, I took advantage of it. Only slightly messed up the position of the cutout because I forgot to account for half the diameter of the cutter...
I'm sure someone could build a controller from an STC-1000 for cheaper than the price of a Ranco, but you'd still have the thing reading in Celsius, and of course, they aren't quite as durable/reliable as the Johnson/Ranco brands, which are more industrial. Mine hasn't quit yet, though, and it's powering up an upright freezer and a small space heater.