As the master of frugal, I can tell you guys about some products that will keep you warm and draw almost no electricity, Shop for your best price or maker of these products.
The 200 watt heater at the bottom of the list will cost 32cents a day running for 10 hours, at 16cents per kilowatt hour, or $9.60 per month, running for 10 hours a day for a 30 day month.
If you sit at a desk when computing then get this foot pad, it draws 90 watts of electricity, but only 45 watts if you buy the extra switch which gives you the option of 45 watts.
45 watts is all you will want, the 90 watts is far too hot.
FOOT PAD http://www.amazon.com/Cozy-Products-FW-Warmer-Heated/dp/B000079896/ref=sr_1_1?ie=UTF8&qid=1418535169&sr=8-1&keywords=heat+foot+pad&pebp=1418535171084
EXTRA SWITCH http://www.amazon.com/Cozy-Products-HI-LO-Remote-Control/dp/B001FOPQQI/ref=pd_sim_hg_1?ie=UTF8&refRID=0C4WD24GTM09NFJQG8XH
200 watt heater that really takes the edge off in a small room, but is very effective under your desk, or pointed right at you. http://www.amazon.com/dp/B0058V9SB8/ref=wl_it_dp_o_pd_nS_ttl?_encoding=UTF8&colid=2EPW9ISNDNSOJ&coliid=IAQGVEA5LKLJ7&psc=1
Right this minute I am in a small office with my 45 watts of foot pad going, and a 60 watt light bulb burning behind me and 18 inches from the back of my office chair for heat, with the laptop and monitor contributing heat. If it were colder, then I would turn off the 60 watt bulb and flip on the 200 watt heater that is 2 feet behind my chair.
BM