Suppose a water jacket, fish tank heater /cooler setup would be cheaper.
Is there such thing as a water jacket that you can wrap around a bucket/carboy? I've seen insulated bags for ice but there's no way to control them.
I just isolate the room from the house and control the temp of the whole room. Window unit and electric oil radiator.
My basement brew room has a window and I could theoretically use one of those "portable" AC units, but I need to get down to the low 60's and that'd be a huge waste of electricity. I did pick up an oil radiator this winter and it helped, but again, I'd prefer to heat the bucket not the room. More efficient and better control.