Garage Heat

I installed a mobile home electric forced air heater.Got it off a buddy for 50$. Keep it @ 40 when not out there, turn it up @ 65 when I am, toasty in 5 min. wall insulated 3.5", 12" in the attic, 22 by 30, 10' ceiling, biggest heat loss is garage door. someday a high$ insulated, will be installed. Last year the highest bill was $108. billed every 2 months, shop has separate meter, not too shabby8)