Don't get all caught up in this "Under Armor" craze. It's a great marketing ploy.
I actually looked for the cheaper version of this material and was unsucessful. So I ended up buying the Under Armor. I thought I would try just wearing the under armor and my hunting clothes the other morning. I was colder than I wanted to be.
Tomorrow, under armor will be my base layer with cotton/polyester thermals and then my hunting clothes.
The only other thing I have to work on is keeping my feet warm. Thats the worst part about hunting in the cold.