My advice is never buy a ready built survival kit; you are much better off building one from scratch. You can hand select the components and spend more on the items you know are more critical to you. Let's face it, no two people have the same idea of the perfect survival kit and they are as personal as they are diverse. There have, in fact, been entire books written on the subject.
In a series of several posts (this being the first) I am going to recommend a pocket survival kit and a slightly bigger personal survival kit. The focus of the first couple of posts will be the larger personal survival kit.
Keep in mind my kits will NOT include luxuries and will provide the basic and most important tools to survive. These are strictly recommendations and you should adjust anything to fit you personally.
There are several components that need to be covered in the personal survival kit. It should be compact, taking up no more space than a small backpack.
The focus of this post will be the container that holds all of the components of your survival kit...the bag. This is one of the areas where choice and diversity are your friends. There is a bag for everyone out there somewhere.
Some people prefer a fanny back but I like the idea of a small backpack myself. The bag should be sturdy and NOT cheaply constructed and I like Camelbaks because of the integrated hydration bladder. Two of my favorite models are the:
CamelBak M.U.L.E 3-Liter Hydration Pack
CamelBak HAWG Hydration Pack - 3L
The HAWG is bigger and will give you more room to play with, the key being you don't want something so HUMONGOUS that is you stop somewhere and walk into the woods and say "Screw this, I ain't lugging that thing in this heat!" That defeats the purpose of even doing this because a survival kit in your trunk when you are in the woods is as useless you know what on a bull.
I like the bladder idea because if you know you are going somewhere, you can pre-fill the pack and have three liters of fresh water to start off with. Many pump filters have adaptors to fill these bladders as well.
That being said, any good quality bag will do; I do recommend a backpack or fanny pack though. It needs to be something that can be fastened to your body and not something that needs to be carried and can be accidentally forgotten.
The bag is one of the most important and personal decisions that must be made in the beginning of constructing your kit. Its size will directly affect the amount you can carry and how comfortably you can carry it, so it is VERY important that you get it right. I recommend you do some dry runs walking around with some weight in the bag to see how it feels carrying it for a period of time.
One other piece of advice, concerning your selection of a bag, get something sturdy but weather resistant if possible. Nothing will be entirely waterproof but something that can keep the contents of your kit dry during a mist or drizzle will help you worry less and focus more on your situation at hand.
Once you have your bag selected and in hand there are several other critical components to a personal survival kit. They will each be covered in deatil in upcoming posts so be sure to check back shortly.
...that is all.