Customer is requesting a controller for Ambient Air Temperature to control heat tapes for a roof. There is a designated 20amp GFCI already mounted to the soffit for the heat tapes to plug into but he is requesting something that will control it by ambient air temp. I have found one so far but it is over $100, he is looking for something cheaper and if i find one cheaper and reliable than i will be installing one on each condo unit "32 units total". Has anyone found such a device and how well did it work? Thanks.