Wrong comparison. COVID-19 is dangerous, but it isn’t currently wiping out the entire humanity. Civilization is still around, so people have the luxury of being able to make stupid decisions. An actual worldwide extinction event will not make us smarter, probably. But it sure as hell will make us more pragmatic.
Bullets, despite being one-use items, will have a considerable value due to inelastic demand. Most people will not have the necessary knowledge and tools to produce a good firearm and ammunition.
As for batteries, I must repeat: disposable batteries should not have the same or bigger value as rechargeable ones. One-use battery is something everyone is capable of making. You don’t even need dangerous chemicals - they mostly are used for energy density, not because there is no other way to make electricity.