A hot air balloon is tethered in the middle of Hollywood Blvd for the world premiere of 'Oz The Great and Powerful.' The special effects wonder cost Disney a reported $325 million, most of which was spent on CGI. - 

Here's a fairy tale with a very unhappy ending. Jack the Giant Slayer -- you know the movie based loosely on Jack and the Giant Beanstalk -- earned about 28 million at the box office this weekend. A disaster considering Warner Brothers reportedly dropped more than $200 million to make it.

A big chunk of that went into special effects. This weekend, Disney takes up the cause with its own special effects wonder "Oz the Great and Powerful." The New York Times reported today that Oz is tipping the balance sheet at $325 million. What can possiblly cost that much?

The trailer promises an eye-poping, 21st Century Oz -- thanks to the wonders of CGI or computer generated imagery. And that comes with a hefty price tag, says Jason E. Squire, a professor of film at University of Southern California.

"There are two major costs to movies, there’s budget and there’s marketing," Squire said. He adds that Disney is probably spending about $125 million for marketing.

As for the rest of the $200 million dollars?

"For a high tech movie like this it basically comes down to CGI," he said. 

Despite  such flops like “Jack the Giant Slayer” and “John Carter” --  a sci-fi movie that was also chock of CGI but that ended up costing Disney about $200 million bukcs  --  studios continue to make huge investments in special effect, CGI and 3D in movies, said Porter Bibb, who's with Media Tech Capital Partners.

"It seems to be the only way that the target movie goers -- 18 to 24 -- will pay to come to see  a movie in a theater," Bibb said. The group makes up 80 percent of the theater going audience.

But with super-high-definition TVs and movies online competing with their attention, studios believe the only way they'll pay for a movie ticket is if it offers more special effects. 

"I'm not sure I buy into that theory," said media analyst Hal Vogel. ""Because the box office, in terms of admissions, has been sluggish now for ten years. " And he says no matter how much money the studios spend on CGI and special effects, tickets sales -- at least in the U.S. -- haven’t kept pace.