Six Energizer 2032 Lithium Cell Batteries | $5 | Amazon
If you have traditional watches, digital thermometers, or anything else that requires power in a small form factor, you’ve likely needed to replace the battery every once in a while. My roster of such devices is so short that I could probably get away with buying this $5 six pack to cover the next ten years, which is equivalent to their shelf life, according to Energizer. These are cell size 2032, so be sure to check what your devices need before playing your order.