Like black-pearls from Tahita or Beluga caviar, cashmere comes from a rare source, Mongolian kashmiri, and that contributes to its steep cost.  It is the highest class of all natural fibers.  It usually takes one goat four years to grow enough hair for one sweater.  Where the fibers are taken from also affects cost-ultrasoft belly and chin hair carry the heftiest price tags.  Also, working with the fragile fibers is an extremely delicate process, from dyeing to knitting.  When the result is aluring, it's worth the wait.