This may not seem like that big of a difference, but when you add up the differences for several different products over several different shopping trips, it starts adding up. This is one of the easiest ways to save money. You don't have to sacrifice anything, nobody is asking you to cut the oreos out of your diet. All you need to do is a little research to find out where to get the lowest price. For your basic items, the "low scale" grocery store is the best place to shop, even if you prefer the nicer one. Maybe you can go to that more expensive store for your fresh herbs because the difference in price is equaled by a clear difference in quality. It's not worth the bump in price when the product is the same though.
Also, sign up for whatever membership card your grocery store of choice offers. Most have a free savings card that is completely free, but can save you hundreds of dollars. They get you discounts on a huge selection of items.
(I used chains from my area, but I'm sure you know where the stores in your area fall in price vs. quality)
Our article was featured in the Festival Of Frugality