There are some items that are very cheap and available locally.
Whole grains store a long time. Wheat is good at least 20 years. Dried corn years, dried rice years, beans years as well. These can be stored in sealed plastic buckets, metal cans, or mason jars with O2 absorbers, and they will be waiting for you when you need them.
Many canned goods have a 2 year expiration date. Buy local and rotate.
Dried pasta lasts a long time. Store in sealed container with O2 absorbers.
Hard candy and sugar both store a long time if sealed.
It is handy to have a grain grinder, my hand cranked grinder cost $20. I also bought several used meat grinders (think wild meat hamburger) for $10 each. Have used them many times on deer meat.
Hit the above stuff heavily, and top off with some of the convenient stuff from the "long term storage specialty item" stores and you should have a good supply.
Clean water and lots of it is also essential, wish I still had that 200' well we had at the old place.