I think both Phaedrus and pforeman make some very good points. The very best kits are those you develop yourself, attuned to your local situation, circumstances, and situation - also the need for something that can serve as part of a quick and dirty shelter. This is often a space blanket and they do function decently for this purpose.

i actually prefer a light weight poncho which is even more versatile. For many years I packed a standard US army poncho, used both as rain gear and often pitched as a shelter. Pieces of light weight painters drop cloths also serve adequately.

One thing to emphasize. If one is embarking an a planned hike, either for just the day or for longer, whatever you are carrying is in effect your survival gear. It is much more than some little box that you open when all of a sudden you are in "survival" mode. Ideal gear components are light weight (or at least not unduly heavy), reliable, and versatile. If you get in a tight spot, you will use whatever you have at hand or can scrounge up from the environment. Your gear should be good for the territory you are in, and for the time of year. My kit for Arizona summers is a lot different from what Phaedrus carries.

I found the price for the kit - 22 pounds which I think is somewhere around thirty US dollars - that is highway robbery; that kit might be worth about five bucks or so.
Geezer in Chief