I just bought the 3VU36 heavy-duty portable electric heater from Grainger for my insulated and drywalled 2 car garage for $134.60. It is made in Taiwan for Dayton. It has a built in thermostat. I plug it into the 60 amp MIG welder outlet. It is large enough to keep me warm.
Phil
"Heater, Space, 240/208 V 5600/4200 W, 19110/14335 Btuh, 23.3/20.2 A, Thermal Safety Switch, 6 Foot Cord, NEMA 6-30P Plug"