We have a heat pump as well as a 'motel air/heat' unit for the Sewing Room. We also have a propane powered fireplace, which in truth, is not efficient at all, and is pretty much only a show piece.
And, while the heat pump will heat the entire 3,000 sqft house, it is very inefficient in temps below 40*. Below 40*, the "Emergency Heat" coil kicks in, and the electricity usage sky rockets.
So, two weeks ago I purchased a 25000 btu ProCom propane heater to inset in the fireplace. It was $350 from Northern Tool on sale. Blower assembly was a $100 option, which I also bought and installed. The blower is interconnected to the heater, which is allows both the heater and the blower to be thermostatically controlled.
What a difference! The extra boost by the ProCom stove supplementing the central HVAC makes a very nice arrangement. It's been 41* here for the last 3 mornings. Shutting the central HVAC down to <60* and setting the ProCom on the lowest setting makes for a cozy wakeup. So far it is using about 2 gallons of propane per 24 hr. period; very inexpensive at the current propane prices. About $0.08/hr. And the central HVAC unit hasn't even come on at all.
There are, of course, much cheaper ProCom stoves that are more generic in appearance. We chose a decorative cast iron unit with gas logs, etc., which of course is twice the cost of the generic units. For a workshop, the generic unit would certainly suffice for my liking. Still, I would opt for the integrated blower assembly, or a ProCom that includes the blower.