What are the taxes and registration fees when purchasing car from a private owner?

Question

(in California)

Answer 1

A private owner cannot charge sales tax.
Nor can they register the car for you.
You take the title to the DMV & they will assess the tax & registration fees according to your state & local laws.

You should call your local DMV & ask them what (if any) other documentation you will need to provide & they should be able to tell you what the fees are for your locale & vehicle.

Answer 2

a way for a owner to make more money off of you