The International Space Station (ISS), at an estimated cost of between $35 billion to $160 billion.
Darmstadtium, is an element. I'm not sure if it's the most expensive but the element only lasts a few milliseconds, making it hard to obtain and extremely valuable.
2 dollars
bioootch
$40,000
It might be a Choprad
a motor bike
fender
newbery
Rachels jeans
One of the world's most expensive shell is Connus gloriamaris
The most expensive pedicure in the world is $225 in Austin Texas, by Allison
The most expensive car being manufactured and sold today is the Bugatti Veyrnon.