When you are comparing prices in the grocery store, also take a good look at item packaging. Can you reuse the container? Will it stand up to repeated use? How many different ways can you put it to use? But don’t forget to take into account whether or not you have room to store a few of the empty containers.
In the South, most grocery stores carry jam and jelly packed in drinking glasses. The jam is the same price as the other low-priced products but once you’re finished with it, you have a drinking glass to add to your collection instead of a jar to throw away. Jelly is the one item which I purposefully buy in glass jars. For everything else I stick to plastic containers when I can. You can be as hard-core a spendthrift as you want. You can reuse everything including your glass jars, but if you have kids the risk of injury outweighs a thrifty benefit.
Plastic tubs and jars are great for saving leftovers in the refrigerator or freezing soups and sauces. I use my large plastic jars to store dry goods like rice and sugar. My family is still using the sturdy plastic butter tubs that my father started saving in 1965!