I worked on a base for almost 20 years. My job did take me occasionally into both the commissary and the BX, but not being a retiree, and being a civilian, I couldn't buy anything (unless I was on TDY to another base, which I did a lot). I can truthfully say that about the only advantage to shopping at either a commissary or a BX/PX was that you didn't have to pay state sales tax on taxable merchqandise. Prices didn't seem any better than the local stores.