Dsway22

Hey im looking to hook up an aftermarket cd player and system i believe i have the premium sound system in my 2007 unlimited x its the 9 speaker alpine but the factory sub in it is an infiniti correct me if im wrong, but will i have to get a premium system wiring harness? If so does anyone know where i can get one for a decent price and not the $100 bucks i would have to pay at bestbuy? Thanks