I have a small emergency kit in my car. It contains: a utility knife, cord, petroleum jelly, bandaids, feminine pads (cheap, great for large wounds), lighters, and a travel size tylenol bottle (fever reducer). The feminine pads and bandaids I had on hand and just threw some into the pack. The petroleum jelly and travel size tylenol I picked up for less than 2 dollars from the cosmetic travel section at walmart, same for the bic lighters. You can get paracord for a couple bucks at a crafts store. The knife is the most expensive part, but you can skip that for now and just get the basic first aid stuff. You should be able to treat most minor wounds, burns/issues with everything I listed. The best part is all of this stuff will keep forever, except the tylenol which you can just rotate into your daily use before it expires. Put everything into a gallon freezer bag and store in the back pocket of a seat or under a seat. You should be able to create this for about 10 bucks total.
You could probably also throw some iodine in there as well, in an absolute survival situation you could use it to help purify water (obviously not the best way, but way better than nothing and it can also be used for wounds so it is dual-purpose).