What kind of affordable snow boot is best for slippery, icy conditions?

I know I need a very warm boot with great traction, it gets to at least -40 where I am. I am having trouble deciding on the right boot because I have never lived anywhere where it snows. We moved with the military and I dont know what I should buy. We cant buy anything expensive, is there a really affordable boot thats good for walking on ice? or attachments you can get and put on boots you already have?