There was a heated-wear store in Olympia,  in the past. 
I think Milwaukee or other major manufacturer makes other battery heated clothing. 
Some rocks out in boiling water,  then in jacket pockets is a start for a hand warmer.  
I hear people used to have baked potatoes for horse riding, before cars, providing a hand warmer and snack. 
The Costco ones are under $80. Costco is meant to be good quality and standing behind their products. 
The first pair was from a Chinese company and were good until the batteries crapped out.