Emergency Survival Tools
The SAS handbook will teach you how to make your own camp tools and equipment. Much of this is made from leather taken from animals you kill. So look over the book and determine what you need to buy to take with you.
This is just the beginning so research the internet for survival guides as they will lead you to life saving equipment and tricks. Just be careful of the hype some of these websites can lay on you. Research thoroughly and read the forums as well. Start by buying the most essential items and build your survival kit from there.