How much will it cost me to get rid of the rattling?

Hello,

There could be a number of components that can make this noise.
It can be due to a worn suspension busing. It can also be due to a loose brake dust shield.
The best course of action would be to do a thorough inspection of the suspension components. Also take a look at the brake dust shield. It is a possibility that it came lose and that what making the rattle sound.

Here is a helpful article:

https://www.2carpros.com/articles/popping-noise

Please do a thorough inspection and let me know what you find.

Any questions please let me know.
Thank you.