This Dice-Shaped Mug, which lists at $12.99, drops to $5.99 with a 54% discount at ThinkGeek. Shipping costs $6.95, but it's free for orders over $75. Even with shipping, this is the lowest price we could find on this mug anywhere online. You don't have to roll a critical hit to get this deal, just order before 8/31 for the discount. The mug comes with a matching lid and holds 12 ounces of liquid. There is no sales tax (except in VA, OH, and FL).