Do you eat lots of things like rice, pasta, and beans?
Then you need to buy it in bulk if you can. The larger quantities will last a long time, and you will not only save money on the over all per servings, and you will save on the gas used in your vechile running to the store on a weekly basis.
Do you need gatorade or powerage? Then buy the powerade not the premixed liquid in bottles. You are paying them for bottle, and for the water used in the bottle. Don't you have water coming out of your tap, or your water cooler purifier? Then that's good too. Plus, you can water it down, so, its not so hard on your body to process the dye and sugar.