With orders of $25 or more, Amazon offers Prime members 10 pairs of Hanes Boys' Ankle Socks in White for $4.40 with free shipping. (Non-members can spend $35 or more to qualify for free shipping.) That's the lowest total price we could find by $11. They're available in sizes S to L.

Note that this item is sold as part of Amazon's "Add-on program" and can only be purchased with an order of $25 or more.