I just did this excursion with my dad this past week. It is an hour bus ride to Fox Studios which was great. A lot of cool sets and titanic was the highlight of the tour. After the tour they bus you to a h otel beach/resort where an authentic mexican meal is served, price included in the ticket, then you have one hour to shop in the small shopping area in front of the hotel. Then they ride you back to the ship or the dowwntown shopping area in Ensanada. Nont sure if you can book indpendently but I'm sure it would cost more than 70 bucks which is what carnival charges.
Hope that helps.