Star Wars cost $11,000,000 to produce in 1977. To put that in perspective, here's how much it cost to produce some other notable movies from 1977.
Smokey and the Bandit - $4,300,000 (#2 highest grossing movie of 1977)
A Bridge Too Far - $25,000,000
The Spy Who Loved Me - $13,500,000
Close Encounters of the Third Kind - $19,400,000
And just for fun, let's include Jaws and Empire.
Jaws (1975) - $9,000,000
The Empire Strikes Back (1980) - $30,500,000
The average budget for a Hollywood movie in the 1970s was about $5,000,000.