Ocean Technology via Amazon offers the Unitek USB 3.0 to Gigabit Ethernet Adapter, model no. Y-3470, for $13.99. Coupon code "YABYMG3A" cuts it to $7.97. Plus, Prime members bag free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $8.02.) That's $2 under the lowest total price we could find for any similar Unitek adapter. It features data transfer speeds up to 5Gb/s.