Sorry to dredge up an old thread...
I was thinking about this, mainly because of the odour factor on longer walks, but also because I have found the famous NZ merino brand to be too itchy next to my skin. (yes, I'm a wimp)

Anyway, the silkbody gear is even more outrageously expensive now, presumably because the cost of silk has gone up due to it's new found popularity.
Or has it?
I found another brand called 'Terramar' which is northern hemisphere centric, but can be bought relatively cheaply at
Sierra Trading Post and possibly other outlets.
The have a dual-layer silk/wool version as well, which has generally
positive reviews (Backpackgeartest.org), but hard to find for sale online.
Am I going to be the test mule for this, or has someone already come across it?
I'll probably buy a pair of each type. If it's cold, I'll sleep in the plain silk and use the dual layer during the day.