One of the tricks of stockpiling is taking advantage of seasonal sales. Right before Thanksgiving, you can stock up on stuffing, gravy mix, boxed mashed potatoes, cranberry sauce, and a lot of different baking supplies. If you want a box of stuffing in, say, February, you're probably going to pay full price for it. After a while, you start to realize what you need to stock up on throughout the year to avoid running out of the things you want.
Sometimes the sales reflect the customs of particular religious groups. I'm Catholic, and I don't eat meat on Fridays during Lent; fish is okay though, and sales on fish are definitely a big deal in most grocery stores in my area throughout Lent. There are many traditional kosher foods on sale for Rosh Hashanah, coming up in a couple of weeks. Even if you aren't Jewish, anyone can eat kosher foods (and actually, many of the things we eat every day are kosher, but if you aren't aware of it, you might not notice.)
Streit's Matzo Ball mix is 10 for $10, and there are Kedem Tube Soup Mixes for 2/$1. For something different and inexpensive, you could make some matzo ball soup and serve it with a side salad or sandwiches. Kedem apple and grape juice are both good prices (1.50 and 2.50 a bottle, respectively) and the Kedem tea biscuits are 3/$1, which would be worth trying. I've never had any of these foods before, but part of the fun of bargain shopping is trying new things and expanding your horizons!