There's plenty of things that will help you survive in an emergency situation, some can be expensive, some could be free or cost less than $2. I'll provide a list of things that are either free or cost you next to nothing that could potentially save your life!
Syran Wrap - Use it to wrap around large wounds, to keep bacteria and viruses out. You can also use for solar water distillation (learn here), waterproofing items, or using it to hang something on a tree. Pour water into the plastic, and wrap it up like a ball, use it like a magnifying glass to start a fire!
Plastic Bags - Carry all kinds of bags, from ziplock to grocery bags, use them to carry items, to wrap around tree branches to collect water (see how here), making a filter, using it for wound protection for your feet or hand just wrap around cord to keep any conaminants out. Endless uses.
Bottle of Chlorox - A small bottle of bleach is very handy, 2-4 drops per quart of water can kill any bad contaminants. Use it to kill viruses on dirty surfaces.
Iodine Liquid 2% - Use iodine to disinfect wounds, gear or even drinking water. Add 5-10 drops to 1 quart of questionable drinking water. (you have to wait an hour before drining, pregnant woman and people with thyroid illness shouldnt drink water that has been disinfected with iodine)
Candles - A batch of wax candles could come in handy, plus they are entirely waterproof! Use it to help start fires, use hot wax to seal openings or wounds, frayed twine or string can be mended with alittle wax so they can easily go into holes, use it to waterproof other items like matches, twine, use it to seal bottles. The list is endless.
Duct Tape - Use it to make bowls or cups, to seal holes or wounds, make pockets, rope, traps, the possibilities are endless. Use as fly traps, etc.
Clear Packing Tape - Most of the uses that ducttape can do, but, clear packing tape can be used to waterproof items like bic lighters. Just wrap the tape around the head of a lighter and squeeze the exess tape together at the top. Waterproof just about anything!
Bic Lighters - I came to the conclusion that if you waterproof your Bic lighter (like i explained above) you will have no problems with starting fires. Bic lighters are highly reliable.
Dental Floss - Preventing gum disease is also important to overall health, but it can also be used to suture up wounds, tie things together, used for traps, cordage, etc.
Curved Upolstry Needles - For patching up large wounds, this is a must have along with sutures/wire/string.
Cotton Balls - Could be used for wound care and starting fire!