The Tomorrowland Tsum Tsum collection is now available via the Shop Disney Parks app. The set was previously released at Disneyland Paris but can now be purchased in the states.
The collection includes Mickey, Minnie, Donald, Goofy, Stitch, Alien & the Claw, and Zurg. Each Tsum Tsum retails for $5.99.
Update: They are also available online at ShopDisney!