Amazon offers Prime members four Old Dutch 16-oz. Copper Moscow Mule Mugs in Smooth Finish for $21.67 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $7.79.) That's the lowest total price we could find by $18, although we saw a similar 4-pack for $2 less in November. Each mug is coated with tarnish-resistant lacquer.