It's illegal for them to charge that.
@t5dude You should leave a review on the FFL with your experience.
https://caguns.net/ffls/
There is a legal
maximum on the fees for a Private Party Transfer (PPT) in California is $47.19, which includes a $37.19 DROS fee plus a $10 dealer fee for each firearm. An FFL may not legally impose any additional fees beyond those allowed by law.
Firearms Dealers Links to Topics below General FAQs DROS Entry System (DES) Internet Process AB 1872/2165/2699 Dealer FAQs General FAQs What are California's licensing requirements for firearms dealers? How much is the annual Centralized List fee and when must it be paid? What is a...
oag.ca.gov
Report the FFLs to the OAG:
https://oag.ca.gov/firearms/contact
"Firearms dealer violation - excessive Private Party Transfer fee under Penal Code § 28055"
AFAIK that's a civil "violation of a statutory duty" if the dealer collected fees expressly prohibited by statute. Seems reasonable to take them to small claims over it. Should be slam dunk with receipts given it was violating CA penal code.