The possibility of viewing a film/movie in a movie theater should come at little to no cost. If cinemas fear losing money they need not to worry because revenue builds up over time.
However on the contrary, it is understandable why a trip to the cinema does not come cheaply. If there was no availability of snacks and beverages in a cinema, it would cost far less, but cinemas charge you more for tickets to compensate for their role of supplying drinks and food.
I can't say what a movie should cost. It's a cost determined be supply and demand. Only the theater knows what to charge. To say a theater should be cheap is to pretend to know all costs involved in running that business. If you don't like the prices don't go.