I'm Navy, and the NEX sells it for $79 I think. My Man is Army, and he bought it online via ako (after a PITA search for the right site), but that only provided a limited discount -- it cost us way more than $79, but I didn't know about the NEX deal then.
the 20 deal for Office has to be obtained thru AKO, NKO or your services equvilant-its on the deals in technology page or something-you can also get anti virus-either norton or mcaffee thru that page-but only if your account is a service members as opposed to a civilian employee, retiree or family member.