Most of us online retailers who are reasonable will offer some sort of military discount if asked. How we handle it is the discount depends on the purchase. If it's something we can give you a 20% discount on, that's your discount. If it's something we can only discount 5%, that's the discount. My brother-in-law served overseas for a year, so I have a soft spot for military men and women for doing what they do, so I try to give us nice of a discount as I can.
I would definitely recommend emailing or calling companies and asking. Plus, the discounts you mentioned already sound really good. Definitely not something to pass up!