Is there any places you know of where I can buy either a fire salamander or a fire belly newt in California?

You can talk with Hoffman's. They may tell you that Newt's an salamanders are more to be left in wild. I know for a fact they have fire belly toads.

Call Hoffman's

Call Hoffman's Reptiles ask for the owner Dan.

Hoffman's doesn't have newts but you can totally call and ask! They should know :)

Not sure call Hoffman's they can help you