First and foremost you must have something between your ears besides slogans and vacuum. All the "Stuff" in the world won't save you if you don't use your brain. I tell everybody to go to
http://www.survivalblog.com/ I have posted a few articles there myself.
After that;
Water, some form of water purification even if that just means the ability to boil the stuff. Google "Field expedient water purification"
Food, yes you may have guns and you may be able to hunt and farm, but can you do it NOW? Will the game be available when you go out to hunt? Food takes many weeks to grow (mostly), so what do you do till the crops are in? Don't waste money buying long term storage food if you can't afford it. Go here
http://www.ag.ndsu.edu/pubs/yf/foods/fn579-1.htm and buy the stuff you would buy anyway.
TOOLS! Do you have what you need to keep your guns running? Your car? Own an Axe (and know how to use it)? Do you have gardening tools, or do you expect the plants to naturally bore into the ground and spring up full blown? Can you turn a deer or fish into food. or do you expect them to spontaneously convert into plastic wrapped cuts of meat? How good are your kitchen knives, will they last a life time or do you have to go to Wally World every couple years? Do you have a shovel? Find what you use or what other people use for you and figure out if you really have what it takes, like plumbing, car repair, electrical work (including converting to use alternative sources of energy like batteries and generators for things like light). I myself have been suffering because I have no axe here in Montana, no axe means no wood for the wood burning stove, that is a major problem for me (but one I will solve next week). Do you have a way to burn wood without burning your house down or suffocating everyone? You can build things to replace much of what society has made cheap for use (food, heat, water, sewerage, shelter) but without tools you may not live long enough to do it.
Guns, for hunting and defense, but also PEST CONTROL, pests eat more food than people and will starve you to death if you have no way to eliminate them. You don't want to risk killing your own animals or yourself with poisons and traps can only do so much. A good pellet rifle is a wonderful thing, and 100,000 pellets is a heck of a lot cheaper than even .22lr's. Don't forget about parts and magazines or you will have some very fancy clubs.
SALT, Matches, Lighters & fuel, without salt you die, and unless you live near the sea you cannot make your own (most mines are contaminated with Potassium Chloride which is poisonous). Most people who think about survivalism think about fire-starters (magnesium blocks, blast match, etc.) which are cool, but a bucket load of book matches and cheap disposable lighters, to say nothing about a Zippo, a few hundred flints and a few gallons of fuel will be far better for day to day use, to say nothing of trading with those of less foresight.
Medicine, including prescription meds as well as the general stuff for trauma and disease. Don't forget your prescription glasses as well.
I'll quit now as this could go on for months. Hit Survivalblog.com for more.