Hard money. Because you know who takes cash? Everybody! A hidden $20 bill in your car could come in handy if you end up in the middle of nowhere sans wallet. Pro-tip: hide an ol’ Jackson in your phone case for emergencies...unless the emergency is that you’ve lost your phone.
This ingenious invention costs around $20 and turns any kind of water (puddles, stagnant lake water) into drinkable water. It’s great for camping and even better for emergencies, as one can even drink sewage water with it. In case you prefer your sewage water purified, of course.