Space, the final frontier

TL;DR ver

• The total cost is expected to be at least $10 billion.
• The development cost of the Mars Sample Return is now between $8 to $9 billion.
• The other billion or two in costs are for launch, the five years of operations, and the construction of new facilities for storing and studying the samples.

About the mission

NASA's Sample Retrieval Lander would touch down on Mars and remain in place to receive a diverse collection of scientifically curated samples of Martian rock already collected and cached by NASA's Perseverance rover.

The lander would be the first ever to bring along a rocket — NASA's Mars Ascent Vehicle — and two helicopters, to help achieve the goal of bringing the samples safely to Earth for study.

source, NASA