I am always looking for products that would be useful if/when things went bad.
Fire can be one of the most important things a person will need in an emergency. A waterproof lighter and water proof matches are a good place to start but I would also recommend a magnesium fire starter. You could start many fires with a single block. They can be had for less than 5 bucks at walmart, cabelas or even on amazon. For that price it is well worth it.
Here is a video I found on youtube of a person showing how easy it is (sorry but the person’s voice is kindof annoying).