Quantity versus price is always a real consideration. What you need to keep in mind as you shop is simple: Buy what you need based on your consumption habits. This brings up the question of buying in bulk. Is it more efficient or does it generate more waste? The answer depends on who you are.
Purchasing items in bulk -- especially dry goods like sugar, flour, oatmeal and granola -- helps combat the problem of packaging. It's becoming more and more common for grocery stores to offer dry goods in bins. You know how much you cook at home and how much food you regularly consume. Buying in bulk makes it easier to purchase amounts you need and can reasonably store. And bulk purchases of such items as dish detergent and canned goods can reduce the number of trips you make to the store. If you rely on a car to go shopping, this is an important step in environmental conservation. If you order online, this cuts down on deliveries made to your home.
Whether driving to the store or shopping online, going in on a bulk purchase with a neighbor is a great way to shop with a conscience. You get the cost benefits of buying in bulk without worrying you are purchasing quantities you won't be able to use.
Don't forget that how you travel to the store is just as important as what you buy.