I sometimes carry some. The KMnO4 I got from a UK chemists without any difficulty, and is relatively easy to store if you can find some teeny, tiny bottles (a little goes a long way). Glycerine is also easy to buy but I found it harder to store because it seemed to leak through smaller gaps than water does. Obviously you need to have a lot of confidence in your containment because it is so dangerous (and will make your kit messy).

In use it works for fire-starting but is not really fantastic. It doesn't go as well in cold conditions. It makes a flame, but it doesn't burn for very long - a few seconds. Not as good as, say, vasaline-soaked cotton plus spark.

To be honest I have it partly for fun value as I like fireworks. Also, the KMnO4 has many other uses; as an anti-septic of varying strengths depending on dilution, and as a dye marker. It is poisonous to fish etc so you need to be careful about it getting into wild water.