Cheap wool warning:

I've gotten a couple Duofold woolies (2 shirts, 2 pr long underwear bottoms) from Sierra Trading Post. Cheap price. Crappy quality.

I'm constantly sewing holes, rips, poor seams, and spontaneous discombobulations on those things.

My Ibex stuff is much much better quality. As is my Icebreaker.

For the price difference, I would go for the expensive stuff.

BTW: I've never had a problem with Duofold two-layer stuff. The cotton/wool double layer that they are known for is great. It's their 100% wool single layer that is just not up to par.