Higher prices during emergencies would make it more profitable to anticipate them and keep inventory around in case of emergency. It costs money to store extra stuff and that cost needs to be paid for somehow or preparedness probably won't happen.
There may be other ways though. In cities where people have limited storage space, maybe consumers who want to be prepared would pay a subscription fee for the option to buy a disaster kit on short notice?
Yeah, I was thinking this may be a good business post-COVID. Let people compose their "survival kits" and subscribe to them; kind of like insurance, but instead of a payout, you'd get guaranteed delivery of the items you listed (or equivalents). Subscription fees would pay for storage, and some of the costs could be recouped by selling off items nearing expiry.
There may be other ways though. In cities where people have limited storage space, maybe consumers who want to be prepared would pay a subscription fee for the option to buy a disaster kit on short notice?