Last November I installed a small pellet stove in our converted garage that is off the kitchen, previously we used a propane garage heater, but the past couple years, used an electric to take out the nip but not really heat it up, but downside, the house furnaces make up the difference, so either way uses Propane, and electricity.
I bought 2 tons of pellets, roughly $400 or so, and ran through about 2/3rds of it, but our propane use dropped, and so did the electricity, and the house was warmer overall. The pellet stove is automatic, so it maintains a 4 degree spread in temps and on the coldest days ran maybe a few hours at most.
This year I plan to put one to heat the whole house, and that should really cut back on Propane and electricity. We have 2 furnaces in the house because it is a long ranch and the main one cannot force enough air down to the back of it. Hoping that with the whole house being heated by pellets, we can bring the cost of heating down a bit and recover the cost in a year or two. I just need to find a unit that uses a remote thermostat for it to work properly.