I could be wrong, but I don't think that these are going to be available for anyone to just "pick up."
I think you have to be a member of the Gentle Giant Premeire Collectors club, and pre-order the bust, and be there in person to pick it up. This is what I have figured out from my looking into trying to get a McQ Fett bust. If I'm off, I'm sure someone will correct me.
I'm really hoping that these are made available to the public after SDCC.