Monoprice offers three Monoprice Pure Outdoor 30-oz. Emperor Tumblers, model no. 15992, for $29.97. (Add three to cart to see this price.) Coupon code "TUMBLER" drops it to $21.99. With free shipping, that's $7.33 each and the lowest total price we could find for the quantity by $23. Each sweat-proof tumbler is BPA-free and features 18/8 stainless steel construction, a double-walled, vacuum-sealed design, and clear lid.
Of note, you can add a Monoprice Pure Outdoor 20-oz. Emperor Tumbler, model no. 15993, to the above three 30-oz. tumblers for a total price of $27.32 with free shipping via the above coupon. That's $39 under the best deal we could find for these items purchased separately elsewhere. The 20-oz. version's features are similar to those above, save for the smaller capacity.