I honestly don't know if there is a price for oil that I would stop burning.
I wouldn't stop burning if it were free. I like it too much. I study fire for a living, and I'm literally transfixed every time I light the stove. There's just something about the phenomenon of rapid oxidation that I cannot get enough.
There are other benefits to burning besides cost that I wouldn't want to give up. I'd be a walking pair of legs because of all the other hobbies I have, were it not for wood to keep my upper body in shape for summer climbing. And I hate going to the gym. Plus I get to spend time with my father which I like. And it's an excuse to quit working on the house and get outside. And use power equipment. Plus I really like cutting.
So yeah, I guess I'm trying to say, the monetary savings that comes with burning firewood for heat is only part of the total sum of benefits. An important part, but not so important that I'd stop were it to be eliminated.