I will second Buffalo equipment, but it takes quite a bit of courage to slip on a Pertex 6 Mountain shirt, in really cold conditions, with just your bare skin below, but its an idea that works incredibly well.
Also, the equipment is not quite the bargain price it used to be.
My Super 6 shirt cost me £64 back in 1995, but it now retails close to £150, which is quite a markup, but it still represents decent value, as it will last many years, and its a bit of kit that really works, in the right conditions.