Love wool, and that is all I use for tech and everyday warmth. Alpaca is my favorite, but I do not use Alpaca on the hill. Merino is more durable.
Costco has some merino wool base layers available, I noticed them last time shopping.
No need to get spendy as they do wear out, as do most base layers.
I personally choose high quality makers (pattagucci, , from special wool etc..