Market/capitalist economy!
If very few numbers of a certain item exist, the price is high. If the item is common as muck...cheap as chips.
There's a story about a woman who was hit by a falling piece of meteorite. As meteorites rarely make it to Earth intact, chunks of meteorites are EXTREMELY valuable, like moon rock. The story is quite sad really, as a bidding war erupts over the meteorite which hit her. Neighbours tried to buy/steal it, the Air Force claimed it belonged to them as it fell from the sky...lawsuits were filed....etc.etc.
Eventually she donated it to a museum, fed up of all the attention.
I think this is the story:
http://www.xenophilia.com/zb0005.htmSo yeah, no matter how useless the item may be, in human markets....rarity equals worth.
Thus ends today's lesson children. You may go play outside for ten minutes.