Mr. Heater Big Buddy propane heater. Get a 20lb tank and the hose kit for it from northern tool. Costs about $120 and works like a champ. 4k, 9k, or 18k btu's. It'll heat that space up, or at least knock the edge off, and is pretty thrifty on fuel (I think it's about 26 hr burn time on 18k...