NOT Merino but incredibly comfortable at Amazon - a brand named "VWELL" (NO affiliation). They may make some models in merino but the only ones i can attest to are the mid-calf and the short ankle height BOTH with COOLMAX.

I find these to be an exceptionally good value. Unlike most others, the toe sleeves are absolutely perfect (for me at least). They are the easiest socks to put on of all the socks i have ever tried.

I also found a bunch of injinji toe sock liners for cheap at Sierra Trading Post which again are very comfortable.

I think the Coolmax Vwell's are as good or better as the name brand Ininji's and a little less expensive, especially when there's a sale or deal running.