The cheap kind...wood. It helps that my husband is a lumberjack too. The only drawback is...it is our only source of heat. That means we can't go anywhere for the weekend in the winter together. One of us is tied to the woodstove. One of these days when we get rich, we will get a backup heat source. I don't foresee that in the near future as I got word that I will only be employed for 120 days at which time everyone here where I work will be out of a job!
Thank god, it costs us nothing to heat our home in times like these.