unobtainium

noun3

1. •
   (humorous) A fictional material or component which, if it existed, would enable one to easily solve a hard problem.
2. •
   (humorous) An especially rare material or component that is outrageously expensive or otherwise almost impossible to get hold of.

   • Bikes made of titanium, once known as "unobtainium" because of its high price, are down from the stratosphere. — 1998
3. •
   (humorous) A high technology component that is extremely expensive.