Yes. Try your local MWR ticket agency or you can buy them at the ticket office at Shades of Green. It's not a huge savings (for a one day pass it's like 65 cents) but you also don't pay tax.
I have found that the best deal for military as far as tickets go are the Stars and Stripes passes that you can get at the Shades of Green. You buy them for however many days you want, and can hop to any of the parks, waterparks, DisneyQuest as much as you want for that many days. You can only buy these passes if you are staying at a Disney Resort or Shades of Green.
Shades of Green also sells Magic Your Way tickets tax free. Their site is www.shadesofgreen.org You can find their prices for all the tickets they sell on the site. I hope that helps/