LL Bean (- a well known and long established US clothing company from Maine) have been using a cotton / wool mix in their 'River drivers shirts' since a long, long time. They use brushed cotton knit on the inside of the fabric and wool on the outside of the fabric. The fabric is very hardwearing. Current RRP about $40.
I bought one in the 1980's, before merino baselayers were available. It was my warmest and favourite thermal underlayer for a long time. Now I find merino has advantages, in that it weighs less, packs smaller and dries a lot faster. I still like the river drivers shirts, but mostly for dossing around at home. My kids have the some of the shirts and love them. In the winter I cannot get my son to wear anything else (-at least not without a lot of persuasion). Unfortunately, LL Bean stopped doing womens and kids sizes 3-4 yrs ago.
Will be interesting to see how this new cotton/merino combo. works out.