They were first brought to our attention during Celebration Orlando in April and now Gentle Giant has officially announced that they will be offering a Luke Skywalker and Darth Vader 40th Anniversary Classic Mini Bust as part of their SDCC 2017 exclusives.
You can purchase both busts in a bundle for $200 or you can purchase them individually if you so desire for $100 each (Luke in his iconic X-wing pilot gear can be bought here and Vader here).
