What would be the cost to each person in the united states to build a death star if it's cost would be 9*10^14 dollars? express your answer to one significant figure.

The Death Star makes me nervous and I'd rather not discuss it.
Let's just do the math.

The population of the USA is estimated as 316.1 million today.

($9 x 10^14) / (3.161 x 10^8) = $2.85 million per person 

Sequoia national park  /  inyo national forest, california, u.s. mount whitney is the tallest mountain in california, as well as the highest summit in the contiguous united states and thesierra nevada—with an elevation of 14,505 feet (4,421 m).