Tanga offers the Rampage Yoga Socks 3-Pack, in Grey/Nude/Black for $8.99 with free shipping. That's the lowest total price we could find by $3, outside the mention below. They one in one size and feature non-slip rubber pads on the soles.
A close price: Present a Gift via Amazon offers them in Black for the same price with free shipping for Prime members. (Non-members can spend $35 to qualify for free shipping; otherwise it adds $5.48.)