Hello Philip! Lunch/Dinner packages are a GREAT way to eat at an incredible restaurant and reserve the "best seat in the house" for a special experience in any of the Disney Parks. If you have never seen Fantasmic! before, you are going to love it!
For the Fantasmic! Dinner Package, you will have the opportunity to book at three restaurants, Hollywood and Vine, Mama Melrose's Ristorante Italiano, and The Hollywood Brown Derby. You are correct in that each dinner will be a fixed price for an appetizer/salad, entree, and a dessert. However, Hollywood and Vine will be a buffet. Hollywood and Vine and Mama Melrose's Ristorante Italiano are comporable in price (around $39 for an adult), but The Hollywood Brown Derby's package will be more expensive since it is considered a Signature Dining restaurant (around $60 for an adult).
For complete details about the Fantasmic! Dining Package, click
HERE.
Have a great time on your vacation, and See You Real Soon!