Anyone who builds AR-15s, the following manufacturers will give you a Military pricing (discount varies) or some discount on items.
Tactical Machining, 80% Lowers,
www.tacticalmachining.com
Del-Ton Inc. of Elizabethtown, NC
www.del-ton.com create an account, tell them you are military via e-mail/phone
Brownells
www.brownells.com (when you create an account, put LEO/Military and its anywhere from 5-15%, sometimes more)
DSA Inc
www.dsarms.com 5% off entire order, must create an account, e-mail/call customer service, and you will be credited at check-out
Nation-wide: Auto Zone, Advance Auto Parts, O'Reilly's Auto Parts, Lowe's, Home Depot, Sally Beauty Supply (wife goes there), Old Navy (1st of the month, dependent IDs work too), Chick-Fil-A, and ALWAYS ASK, it never hurts to ask! Some cashiers will give you a discount based on their personal support for the military, not the corporations!