One of the best tips I can share with you about stockpiling in the summer is to purchase berries when they are at their rock bottom price (for your area) and freeze to last all year. I always purchase large quantities of raspberries, blueberries, blackberries and strawberries and then I freeze them and stockpile them to use all fall/winter/spring. You can purchase at the grocery store, farmer's market or a pick your own produce patch. I also supplement with growing my own.
Stockpiling Tip - Freeze Berries this Summer:
Here is a how to freeze berries post which gives you a step by step guide on how to flash freeze your berries. I hope it helps you save big on your grocery budget!