It is important to point out that freeze-dryed food and dehydrated food are two VERY different things. Dehydrated foods have a shelf life of maybe 6 months - freeze-dryed foods up to 30 years.
Also, it should be pointed out that freeze-dryed foods really only fit a niche of the prepper's food spectrum - the "light weight / long shelf life" niche. More basic and fundamental than that (and more affordable) is vacuum-sealed beans and rice - along with a pantry full of canned goods. (Properly stored dried beans and rice can also have a shelf life of up to 30 years.)
If you research the nutritional value of beans and rice you'll find that combination to be almost a perfect food (well, throw in a few vitamins, then you've got it made!).
I’ve easily gotten more than months, by vaccuum packing my dehydrated stuff in canning jars and adding an oxygen absorber to the jar. Should easily be good for two to three years. True rice and beans are more nutritional value, longer storage life and so on, but pretty bland by themselves, throw in a cup of mixed dehydrated vetables in your rice, dried peppers in your red beans or dried onion in your white beans, or a can of spam fried up with some dehydrated onion and potatoes and you got a much more palatable dish.