It depends on what you call a "thing".The most expensive single object is the International Space Station (ISS), at $157 billion. However, it is not complete. It is expected to be done in 2011 (as of January 2011). The most expensive completed object is the Itaipu Dam in Brazil at $27 billion.
But antimatter is the most expensive known substance. It is $62.5 quadrillion a kilogram ($28 quadrillion a pound).
life is the most expensive thing
A Super Nova, exploding star, is by far the most destructive thing in the universe.
The most expensive is their blazers.
Life
The unknown.
Antimatter
platinum
pussie
a black and white hole
Hasmter are the most adorable thing in the universe
Duuh The Universe
gold