The group says nearly all the country's major TV and movie studios are among the most recent contributors to the roughly $9.5 million it's raised so far through donations and government grants.
Steven Spielberg, the Lucasfilm Foundation and Tom Hanks also contributed.
The group hopes to buy the land from its Chicago area-based owners and give it to the city, so it can be incorporated into the adjacent 4,200-acre Griffith Park.
Its option to buy the parcel expires April 14.