May is Case Lot Sale month at the military Commissaries. Good deals can be found but be sure to know your prices - they aren't always the best prices, and you don't want to stock up if you are PCSing this summer!
Click here for the list of sale dates. If you click through, you can see if it is being held at the store itself or if it is being held a separate location. If you are travelling a distance, call before you go. Case Lot sale dates sometimes change unexpectedly! Also, you can sometimes get an advance list of products and prices at the commissary the week before the sale. This definitely makes it easier to comparison shop.