A good question.
I tend to agree with HannaLee.
I only buy what we actually eat on a regular basis and tend to buy ingredients rather than completed foods. This was spurred on (especially in the beginning) by being rather poor. I can not afford to let any of the food I pay money for or work to produce spoil. A few freezer burnt steaks and a gone too long jar of canned goods represents too much investment of my time and money for me to lose.
So I usually try to keep a steady rotation of food coming in and out of my house. I faithfully inventory and rotate all of my freezer goods and pantry stores. This means I will never be storing things for much more than a couple of years at a time and that is a long time for us a year and a half are more typical. Since we are constantly eating it I don't skimp on the good stuff.
When we were first married (as teens) and very poor I bought cheap food. Then I realized two things. First it is better to eat the best food possible and not waste any than it is to buy the cheap stuff just for flavor sake. After all, eating delicious foods is one of the true joys of life, so why compromise your life for money. Instead learn better cheaper ways to acquire that delicious food, like growing your own!
The second thing I learned was that the better the food, the better the nutrition! It is very important to eat a healthy diet. A healthy diet made up of fresh high quality foods helps us to stay strong and healthy and THAT will save you money. If we are just worried about shear survival foods all we would need to do is store a big vat of purified water and several hundred bags of the best dry dog food we could buy. The nutrition in that would keep us alive. Not so sure that it would be much of a life however and now we are back to lesson #1.
In a normal short lived emergency situation (and we have had instance to prove this with a 10 day no electricity nearly lock down ice storm) we live pretty darned high on the hog! While others in my area were eating peanut butter for days at a time or going to shelters or to stay with relatives, we were warm by the fireplace eating roast beef and potatoes and having cake for dessert.
If we ever have a true TSHTF emergency first I plan on depending on God to care for us and supply our needs. After that I figure I have about a year or two. After that time my glasses will be broken, my arthritis will swell me up and I will be the crazy old lady people go to to learn how to make soap and clean chickens.

At that time I will simply be bartering my knowledge for food to eat. The knowledge is what I am storing the most of ... that stuff won't rot on the shelf!
