I use a ceiling mounted infrared radiant tube heater to heat my 24X32 shop, like this
http://www.sunstarheaters.com/product/sir-series/ It's set at 38F when I'm not there. Within a couple minutes of turning it on you can feel the heat, set at 50-55F when I'm working. My Waiex is almost directly under the heater so it warms very quickly. I use 100-150 gal/year propane.
I'm considering a mini split heat pump as well to use mostly in the summer for humidity/cooling in the shop, like this.
http://www.fujitsugeneral.com/us/reside ... index.htmlwe have one in our home and it works great.