[Well..."common sense" isn't always so common, especially to the disoriented and the scared, of which this town has plenty. He felt it might be worth mentioning.]

They're all you'll be given, but it's certainly possible to find or make more. The things you find in buildings tend to be things you'd expect to find there, but it's entirely possible to find something that certainly wasn't there when you last checked. The administration distributes these items for us, though why they are left to be found rather than given to those who need them directly doesn't...ah, doesn't cast them in a particularly flattering light.