Los Angeles rent controlled cash for keys

[David Shaw]

Hi, first time posting, long time following the great advice here. 

I own a 4 unit in rent controlled Los Angeles and I am looking into cash for keys for a tenant that has been there for 8 years. 

Looks like it's more complicated in Los Angeles, and many use a company or lawyer. One company quoted me $2500. I wanted to see if anyone has any experience/guidance for doing this? What are typical costs, should I be using a lawyer in Los Angeles with all the regulations, and any idea what amount can be offered to the tenant? 

Thank you in advance!