I spent a bit of time last week making a heating pad out of two $1 bandanas (one for a pillow case), half of a $2 bag of rice, and some chamomile and mint teas that no one was drinking.  If you are poor and cold a lot, THERE IS NO REASON YOU SHOULD NOT MAKE ONE OF THESE.  Here are the instructions I used (although I segmented the bag and added some tea to make it smell nice), here are some instructions to make one out of an old sock.