ThinkGeek offers the Star Wars Death Star Heat Change Mug for $3.99 plus $5.95 for shipping. That's $9 off list and the lowest price we could find. When cold, it displays the Death Star with Superlaser firing. When warm, the Death Star's laser strikes Alderaan.
Bed Bath & Beyond offers the Underground Toys 22-oz. Star Wars Stein in R2-D2 or Darth Vader for $19.99 plus $5.99 for shipping. That's the lowest total price we could find in any style by $24, although we saw it for $6 less in December. It features a metal hinge.