Portable heaters.

I went from kerosene to propane a couple of years ago, and like it alot better.
I do leave the garage door cracked when using the heaters.
Nice thing about propane here it is cheap, $12 to fill a standard gas grill bottle.

I have a heater very similar to this one, and it is in your price range.

http://www.northerntool.com/shop/to...m_content=20587&ci_src=328768002&ci_sku=20587