Injinji -- Good sock, horrendous price
Injinji's are nice, but they have cornered a market and are abusing prices.
Bamboo silk 5 toe socks. For those who use these to run (esp. with Vibrams), these socks are ideal. At $9 for 4 pairs, they are significantly cheaper than Injinji's. The bamboo silk is naturally anti-bacterial, breathable, and stays dry. In addition, the weave seems to grip the feet better and reduce rubbing.
Injinji's: a good sock, but someone here is taking advantage of the price.