I haven’t bought or sold much on SON, but from my observations - “Fair price” and “SON” do not belong in the same sentence.
To answer the originaly OP’s question - the price range you could safely start with would be in the realm of $7000-$9000 depending on condition of your car.
Also, I’d like to add that most private sales are open to negotiations. There’s the rule of thumb of “placing an asking price of higher than what you expect” - on the other hand (from a buyer’s perspective) - “offer less than what you actually expect to pay.”