I use a heated vest from BlazewearUSA.com and I absolutely love it. Great price, good battery life, and the warmth saves you from needing to go warm up inside so you can stay on the slopes for hours! They have other great products too like heated socks, gloves, scarves, and even heated glove liners you can put in any gloves...

http://www.blazewearusa.com/heated-a...er-sports-vest