Post 9-11 what are the cheapest urban survival caches? Storage lockers at transit stations or gyms? Private mail boxes whose address you never give out? A box entrusted to a third party?

Where can you get a small and secure space to stash gear and supplies that you might need to get to in an emergency?

Edit: This would be separate and additional to your EDC and BOB stuff. Assume for example that stuff runs out or you are separated from it. Or maybe this is where your BOB lives.