I have had good luck with an "oil filled" electric heater. Because of
the oil it produces low temperature heat that doesn't "toast" the wood
dust. The large fins and wide spacing make it very easy to clean. The
heat is even with no drafts or blowers. They come with thermostats and
usually cost less that $50. Max size for a portable (plug in) is about
1500 watts. They are available in a baseboard version but I have no
experience with that model.