I have a reply in this post called 2 of the 3 car kits on another board. It may give you some idea what you might need.
Car Kits.

OK now how to work a complete kit into your budget. First prioritize the items you want to include. Get the most needed items first. Nothing says you have to get the entire thing all at once. You can build it up a piece at a time until it is complete. The first items can be relitively inexpensive one use items. You can always upgrade to higher quality later. Notice I said inexpensive not cheap. Cheap junk that fails is no bargin. It could really cost you in the end.

I know the three places you can go where you might find what you need at a bargin price. The various Dollar stores. Sure much there is junk. But some items with a little imagination might fill in a hole. Pawn Shops. Who knows what might be available? You need to check back often because of turn over. Thrift/Salvation Army/ Goodwill Stores or whatever they are called in your area. Some really amazing things are donated to these stores and sold at truely low prices.

Something I really like for the car and has a multitude of uses is the Spetsnatz shovel from Cold Steel. Relatively cheap and can be used as a shovel, pry bar, axe, and defense. For car carry, I like it a lot better than a U.S. trifold. With snow difts a possibility, a small shovel should be mandatory anyway, but this is really decently made and has a stout (non cold transferring) wood handle. I had to take a good file and sharpen the chopping edge, factory edge was pitiful. It'll easily remove limbs from a fallen tree or chop a hole through safety glass to extricate yourself or someone else. Definitely worth the money.

If you wear glasses, or need reading glasses, a extra set, left in the car, is a good idea.
Good Sun Glasses left in the car
Sun and bug screen
A weeks personal meds that can be packaged and left in the car. Handy if a unexpected overnight occurs
Cell phone and car charger, with a phone number list
Extra clothes, clean socks and walking shoes or boots. Clothes for colder than expected temps.
A rain jacket, rain suit, or poncho
JED flashlight with extra batteries
bottled water
Toilet paper/big baby wipes, 2 gal zip lock bags come in real handy for commutes
Good detailed, up to date road maps for at least the area several hundred miles around your driving route. A small compass can help when you aren't sure which way is the right way when lost.
A good, matching full size spare, not a small emergency 'donut" spare.
Extra car keys somewhere on you, in a wallet or taped inside your belt,. You never know when your keys may be lost or broken
Small Tool kit
A 6x9' trap will help keep you clean when doing emergency car repairs on the road.
A good book or 2 for those times you are sitting on the highway for a few hours due to construction, or a wreck stopping traffic
A small FAK with Imodium AD and pain meds in it.
A travel tooth brush, paste, and dental floss come sin handy, esp if you get something stuck in your teeth while driving.
Cash, in small bills, hidden somewhere in the car, just in case you lose your wallet/credit cards. I call it my "get home" money. I have a old photo drivers license hidden in my car.

I already have something like it, or better. An army surplus shovel. East German. Very heavy. Gift from my mother-in-law. I used it one winter when we had an ice storm. Our lightweight Sears Hardware garden shovels bent. Not this baby. This one would take your head off. It chopped thick, hard ice very easily.

"This one would take your head off. It chopped thick, hard ice very easily." Don't tell anyone, but that's one of the things that a mil-spec shovel is designed for. At hand to hand range a mil-spec shovel is damned effective against anything. Two or four legged.

The shovel is HEAVY, which is also quite a drawback in a townhouse development like ours. Lots of kids around all the time. If you're taking a good swing at some ice, I have to make damn sure no one is standing too close to me in case I loose my grip and it gets away from me. The soccer moms would take MY head off.

Where do you park, Fort Apache - The Bronx? <img src="/images/graemlins/shocked.gif" alt="" />

as others have said - the basics are where to start - some duct tape, antifreeze, basic small tool kit

Other CHEAP things to add - a roll of toilet paper (I'm serious) in a ziplock bag, a few rags/towels, a package of baby wipes(yeah, even for you single guys), at least 2 L of POTABLE water - and in winter - thow a spare wool blanket in the car

Other than the blanket - I think I added about $5-7 to your list

I already possess these items and always keep the tank topped off. Hey, not bad. <img src="/images/graemlins/smile.gif" alt="" />

-- Craig

A male urinal? I've never been in that much of a rush to get anywhere where I couldn't stop at the next gas station to use the restroom <img src="/images/graemlins/grin.gif" alt="" /> I would carry toilet paper or tissues though, just because there's really no substitue for it when you really need it.

The Forester already has underfloor compartments where you can fit a lot of this stuff. Most of my tools, emergency kit, tow strap, and other stuff fit in one of the comparments, or in the center bowl of the spare tire.

If you get snow in your area, carry chains. Even with AWD, you'll can still get stuck.