If you have birch trees where you live you’re in luck – you can fill a baggie with birch bark fire starter for free.
It’s highly water resistant, and has lights easily due to it’s resin content. Birch bark also has fungicidal properties that prevent it from rotting, which means that a small bundle of it in a ziploc baggie will last years in the bottom of your backpack. Make sure you collect birch bark that is already hanging from the tree. Do not peel birch bark from around the trunk, as this puts the tree at risk.