I am recently been offered to take over or at least I think get an option to buy from the dealership a A4 2004 Ultra sport , Dolphin grey. 25K on it. For $19K. Is that a good deal? if yes if I buy it do I have to pay taxes again?

The question really is that would I save money if he buys it from the dealer and then I buy it from him. ( With financing from the bank for private sale) or Buy it directly from the dealer and give hin the rest of the money since I know the $19K price have been paded. (Financing for dealship buy? ... will I aslo pay taxes on it? ?

Help .. I love how the car looks, built and drive.