AMS is the company who gets the stuff. The stores aren't run by Disney themselves, rather they sell the stuff to AMS to sell them. AMS has dealings with Sony and Universal, and a bunch of other companies. They do have a permanent store in Fullerton and I think the Vegas store is permanent, or there for a very long time.
The one in Hayward had stuff from a big & tall type store along with their Disney stuff, and like Adelade said, the Citrus Heights store had west coast choppers stuff.