Some people think, "Why should I prepare? If something happens, I can stock up then." This is not the case. For example, I live in a part of the country that gets snow usually a dozen times or so every winter. Still, every time snow is predicted, most of the people in the area are rushing to the stores to stock up. By evening, there are a lot of empty shelves in the stores. And that's just when 2 or 3 inches are expected! Can you imagine if a blizzard was expected? If a nuclear event was a serious possibility, I can't even imagine what the stores would look like.
I used to make $10.95 an hour as a manager in the food service industry, but I recently left this job because three years was too long at that stressful place. Now, I am an overnight stocker at a Wal-Mart (where I work fewer hours for less pay), and I can tell you, stores don't have a whole lot of stuff on hand. From one night to the next, I see how much of the food has been bought, how much is still on the shelves, and how much is in the backroom. There is probably enough to service normal shopping needs for 3 or 4 days without another truck. Except for water. I cannot believe how much bottled water sells each day, and that's without an emergencies! Unprepared people who panic at the possibility of a nuclear event could completely empty the store (which is a Supercenter) in a 24 hour period.
So, please, heed my warning. Even if you don't have much money (like I don't now) you can still prepare. Buy 1 extra can of something you buy each week. If you drink soda, buy 2-liters and reuse them to store water. Buy 1 extra of non-perishables: when you buy soap, toothpaste, shampoo, etc. buy an extra. It may take a long time, but any step toward being prepared is a step in the right direction.