Dayton controls has a ton of them, reasonably priced. I think the ones I used had a 22A resistive rating. Just pick a cooling or heating/cooling (SPDT) with the temperature differential that you want. They aren't at all aesthetically pleasing though. Ours came from Grainger. We use PSG Accustat units where we want fixed heating/cooling settings away from tampering fingers. They are not what you need here but are available in line voltage units, with up to two stages of heating and/or cooling.
Joe
