Look around for those small spice tins that have long been used for pepper, sage, chili powder and other condiments. McCormick, the big spice company, is replacing the last of the metal tins with plastic ones this summer. Most of the tins—which were first made in 1911—were replaced in 1985. But McCormick kept the tins for pepper and Old Bay seasoning, a brand it bought in 1990. Now those last two are also about to disappear. As a result, the old tin boxes may be worth $25 or more as collectibles. Look for them at flea markets. Or, even better, look around your kitchen shelves, or the shelves in your parents’ kitchen and the kitchens of elderly relatives.

You can even check grocery stores for the tins. McCormick is selling the tins until supplies run out, so there may still be some available at regular retail prices of $2 to $5—although it will likely take five to 10 years for those to increase significantly in value.

For maximum value, tins should be in original condition, with perfect paint, no rust and no dents. Never wax, paint or apply a protective coat to the tins—that ruins their value.

Be careful not to damage any stamped markings, such as a use-by date, which can show how old a tin is. Dry tins thoroughly and store them safely—nowhere that is humid, which can lead to rust, and not in a sunny window, where the tins will fade.