Would this be expensive for a movie?

So I'm wanting to make a movie that takes places during the
1920's-30's period. I want to keep the movie as authentic as possible.
It's about prohibition and the influence it had on American organized
crime. So I'm gonna need guns from that period as well as cars. How
much do you think production cost would be? Do you think I would have
a hard time finding someone to produce the movie?