I suggest you purchase reusable canning lids. Lids would be hard to come by if SHTF. Another good way to preserve food is drying. We grew a lot of soup beans and dried them in the shell on the plant. Sunflower seeds are good too. Corn can be dried for cornmeal. We bought a rocket stove in case we ever had to can without the benefit of a gas or electric stove. It's great your wife loves canning! We usually can hundreds of jars of fruits and veggies, but it is very time consuming and very physical work. I'm getting kind of old to do it in the scale we have been doing it for the last decade. I think I will take a break next year.