We all know that you can drop a wheelbarrow of money on a Mountain House Foods dealer and get a ready-made supply of freeze-dried food, good for 20-30+ years of storage in the ever popular cool, dry place. This sort of food has a place in my storage plan, but trying to have enough to feed more than 1 or 2 people for a year is going to eave a huge dent in your wallet. It's also going to get more than a little boring. Despite the fact that the food is of good quality and quite palatable, the menu is rather short.
Most of the food you can buy in the grocery store is either good for a couple of years, or will require special repackaging in order to keep longer. This strategy works, but at a considerable cost in time and effort, something many folks may not have to spare. Face it, dehydrating, packing buckets and the like are time intensive, and the materials are not available at the local Big Box Mart of your choice. You're going to order them from somewhere on the Intertubz, and there goes some of your savings. Add in your time, and the Mountain House route starts looking better (except for that mountain-size ding in your budget).
Bison Survival Blog has a good guest post listing some of the grocery store items that can be stored in quantity for long periods of time without special preparations. There are other items out there as well that aren't on that list, such as white rice. (Sorry, brown rice lovers, it just doesn't keep as well over time.)
There are numerous sites out there catering to the prepper on a budget (Google something like "long term budget food storage" and stand back), so I'm not covering this in any depth. I just want to point out to any strangers who might be happening by the place that preparing for bad times doesn't have to cost an inordinate amount of money--indeed, it can be done with relatively little effect on your budget when done well.
Which means there is no excuse for not having at least 3 months of food on hand.