Here are a few examples.
1. We love Crystal Light- we do not drink soda or tea at home ( i do drink it at work) so we only drink water and crystal light. However, if we had to buy it regular price it would really add up in price! Since we mainly only shop at Publix, and they don't have a store brand of the drink mix, we either have to stock up or else! The good thing is that generally it will go on sale(buy one get one free) every 4-6 weeks. We've noticed this pattern, and now when we see it on sale, we buy enough to make it to the next sale. This is actually a much cheaper option than driving to Target and buying the store brand there, or having to go to another grocery store when it is on sale.
2. Spaghetti sauce- We don't really eat pasta too often at our house, but we use this staple for many other things- making homemade pizza on the weekends, dipping sauce, lasagna, ect. I found out a long time ago that there IS a difference between the Prego/Ragu varieties and the ones I consider "nicer" brands such as Barilla, Classico, ect. So of course i would like to only buy the nicer brands yet we don't want to pay 2-3 dollars a jar for spaghetti sauce. Since we like several brands, there is almost always going to be a buy one get one free sale at Publix. So we just buy as many as we expect to need for the next month or two at half the price (and CHEAPER than the other brands). There are rarely coupons for pasta sauce, but of course if we have them, it makes for an even better deal.
For food products, obviously you need to think about expiration dates, but most canned/frozen/jarred stuff lasts a long time.
A huge way that stockpiling really adds up is health and beauty care items (i.e. deodorant, shampoo, ect). I have basically decided I'm only going to buy these things at a very low price, but this only works if you are able to have the items you need in the closet for when you'll need them. Otherwise, you'll be running out to the store and paying 4 bucks for a bottle of shampoo. I'm not very brand loyal on toothpaste, ect so I am able to usually get the tubes for almost free after the ECB from CVS. Whenever I have a good coupon for razors, deodorant or shampoo i hold on to it until i find a good deal and then stock up!
This isn't a very good picture below, but it shows one shelf of our hall closet where we store stuff- at any one time we have multiple packs of razors, deodorant, toothpaste, shaving gel, contact solution, ect. Another shelf holds shampoo/conditioner/styling products, baby shampoo/bath, ect.
Try it! When you see a good deal, get what you think you'll need to make it for the next few weeks and avoid paying full price again!