Portable Heaters can be expensive. Here is a tip to make a cheap and effective heater:
Use a standard size metal coffee can, a roll of Toilet paper and some De-natured Alcohol. Put the roll of toilet paper in the can and soak it with the alcohol, until completley saturated. Lite the toilet paper and enjoy the warm orderless heat that is provided for several hours. More alcohol can be added (when the fire is out and cool). The saturated roll of toilet paper can be re-used several times before needing replaced. Save the coffee can lid to keep the alcohol from spillling when transporting.