I use a propane Readyheater style "salamander" with 70,000 BTU and it does a good job. I like the propane type better than the Kerosene type because there's less smell.
The best bet is to get an old wall furnace (ebay) that you can vent out of your garage. Even the propane fumes will get to you if it's not vented.
My father-in-law just installed a vented corn burner. It was quite a bit more expensive but it is awsome. He also heats his basement with it. Check Harbor Freight.