buying Audi A6, 1999, 96k miles, need suggestions

Hi Friends, I am buying a 1999 Audi A6 Quattro with 96k miles. need suggestions about the things to keep in mind before buying it. timming belt on this car has never been replaced. does anyone know how much it cost to replace timming belt, water pump etc. what should be the price I offer on it. the car is in southern california. Thanks