American infantry have found that spending top dollar (as in $20, or more, a pair) for socks is a good investment. This is especially true in Afghanistan, where infantry spend more time doing foot, rather than vehicle, patrols. The terrain in Afghanistan is also a lot nastier than what was encountered in Iraq. Many of the troops who first arrived in 2001, were already wearing these high tech (layers of soft merino wool on the inside, with nylon and elastic on the outside) socks. Originally developed for hikers and those who work a lot outside, troops have been buying these socks with their own money since the 1980s. These socks are rugged, comfortable and designed to wick moisture away from your feet and prevent friction.
In the last few years, the brass realized that the usual military grade socks were no match for these high priced, multilayer products, and decided that it would be good for morale if the government began buying socks the troops were actually wearing. Brigade commanders have money for "special equipment" like this and troops headed for combat zones get lots of special stuff. For many units, this included some high-end socks. However, there are several brands out there, each a little different. One type does not suit all, so the troops continue to shop around. Foot comfort is important for an infantryman, who usually has more important things to deal with than blisters or soggy feet.