How much would it cost to build a Death Star?

Yes, 852 quadrillion. Not sure how much that is in quatloos.

The short answer - a lot.

The slightly longer answer: $852,000,000,000,000,000 for the steel alone. That many zeros translates into quadrillions. It also amounts to about 13,000 times our world's gross domestic product, according to the folks at Centives, who decided to tackle the question of constructing the ultimate weapon from the "Star Wars" movie series. Centives is a blog operated by economic students at Lehigh University who apparently have too much time on their hands.

For all the mathematical details - and the answer to whether the Earth contains enough iron to even build a Death Star - click on the Centives link above.