Ibex just approved me as an affiliate so go forth and stock up on merino wool! Use code DCWOOL for 15% off.
Ibex makes some great stuff for those of you who have never tried it out. Their stuff tends to be a tighter weave than Icebreaker generally uses, so it will hold up better and block wind better, but is not as soft. All their stuff might not be like that, but that is my experience poking around on the racks whenever I see Ibex in stores.