The Dragon Ball Z x G-Shock GA-110JDB-1A4 is one of the most popular collaborations of the year, and the GA110JDB-1A4 (U.S. release) has been selling out quickly. In case you missed it at Gshock.com and Reeds, there are still a few places that have it available online.
Zumiez has it, and Amazon seller Orva Stores is offering it (available on Prime and fulfilled by Amazon) without jacking up the price like some other sellers.
Update: The GA110JDB-1A4 is no longer available at Zumiez or from Orva Stores, but it is still available from other sellers on Amazon. Reeds Jewelers also has it in stock.