I just put up a small 12' x 30' shop building. I'm going to use if for storage as well as a shop to do my refinishing in. I have it insulated, wired for power and plumbed for propane. I need some reccomendations on a small propane heater.
You can use a regular furnace with some ductwork and a LP conversion kit. You could install a A/C coil with the furnace in case you eventually want to add a A/C. Really depends on how much you want to spend. You could use a Reznor style hanging heater which would be more "cost effective." If you want I can price a Reznor for you. PM me in your interrested.
I have a 12 x 24 workshop that is insulated and I heat it with a 4000 watt in wall heater. It heats it up very quick and wants it is up to the desired temp it does not kick on that much. Here is the link to the one I have. I know its not propane but it works really well and does not take up any space. Shop Broan High Capacity Wall Heater at Lowes.com