Answer:
Of these things - I have two. One for me - and one for you. And when you ask about the price I simply smile and nod twice.
Some try to hide, some try to cheat, but time will show we always will meet.
I am taken from a mine and shut in a wooden case from which I am never released. Yet I am used by almost everybody. What am I?
You use me between your head and your toes the more I work the thinner I grow.
I am always hungry I must always be fed. The finger I lick will soon turn red.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?