Provisions is a great natural food store. They don't have a huge inventory but you'd be suprised at how often they have exactly that rare thing you're looking for. Great cafe section with vegan food and free range meats. All organic vegetables. Amazing smoothies and very good organic juices. Prices very good for organic in the Hamptons. For a quick lunch, pesticide free, this is the exact spot in Sag that you're looking for.