Get some reloading tools and plenty of components (cases, propellant, primers, bullets) for every caliber you own. Lee tools are cheaper than other brands but they make just as good ammo as the big name brands. I have some Lee tools for .45acp ammo that I bought in 1962 and they still work good as new.
For some unknown (but imho suspicious) reason factory ammo has been in short supply ever since OhMama! took office, but components for reloading are not too hard to find. Although the components cost close to twice as much as before OhMama! took over, I think that's probably just the supply and demand market at work.
Thanks for the advice. I had not considered reloading but clearly if the SHTF it will be a very valuable capability.