REI offers the Thorlo Men's Experia CoolMax Mini-Crew Socks in White or Black for $3.83. Opt for in-store pickup to dodge the $5.99 shipping charge. That's the lowest price we could find by $9. They're available in sizes M to XL, although not in all size/color combinations.
REI Garage cuts 50% off a selection of footwear, with prices starting from $4.73. Shipping adds $5.99, or get free shipping on orders of $50 or more. (Some items are available for in-store pickup.) A couple of best bets, both with free shipping: