Wretchard and his commenters are discussing what to do before there is a breakdown in civilization. Of course there is the usual - buy guns and ammo. But what else could help?
Stock up on tools. Even cheap Chinese stuff if it is not too junky. Voltmeters and for those who are somewhat adept - oscopes.
A good shortwave radio. This is good at under $150
Once you get your radio buy spare alkaline batteries and practice using your radio. Like any tool, the more experience you have with it the better it will serve you when you really need it.
If you can fix things or make thing - good. Plumbing, house wiring, simple house repairs. Auto repairs.
Tools, tools, tools. Most of them that will be useful don't have a rifled barrel.
The Anti-Idiotarian Rottweiler
Don?t bang your head!
The most valuble will be hand tools for gardening and seeds.
Hugh