2005 530i. Just bought it used. I have a service light on and when I went through my onboard display. It said there's an exhaust leak. I live in Los Angeles and Pasadena, CA.

What's the cheapest way to diagnose and fix this problem and then to reset the service light?

If I get my reliable mechanic to find the leak and fix it, then can I get the service light reset for $30.

One shop in Eagle Rock told me this and it seems too expensive:

If you just want us to clear the service engine soon light with no
diagnosis then it will be $47.50. If you want us to extract the fault
code and no diagnosis it's $95.00. If it's a simple fix and you
authorized the repairs, then the diagnostic fee will be waived only if
we don't spend more than an hour on actual diagnosis.