Also they can be purchased and activated at any Disney Guest Services location. There are 2 at DTD, and at the 4 park gates.
The savings thru a military base or SOG purchase is usually just the sales tax. If you are at WDW and want to go over to SOG just to get the tickets, you will waste lots of precious vacation time. I'd say at least 1-1/2 hours. Plus they would still not be activated until you went to a Disney ticket outlet or GS, so more wasted time. I would recommend getting them ahead of time on base and activating them at Disney, or thru Disney upon arrival to WDW.