I have a family member in the military and can use a commissary, but the base is about forty minutes away. If the difference isn't too substantial I would rather go to the close Wal-Mart.
Stuff is usually cheaper at walmart than at the commisary. The advantage of the commisary, is that you don't pay tax on anything.
Way back in the olden day's when I was at Schofield Barracks ...lol..but it was a long time ago..we didn't have a walmart but milk was nearly 5. a gal off base and 2. on base...I guess that's cause Hawaii has high prices..
parking was a challenge at the commissary,getting thru the crowd,lines, and then sometimes after an hr in line,someone called in a bomb threat and we had to leave without getting any groceries.
funny memories now..anyway..Walmart has great food prices..but if I were you I would go to the commissary at least once and check it out ,take your grocery list,write down prices of thing things you use the most and compare to walmart to decide..it's worth going once to just know I think.