You could make a business plan and cater it to making a movie. I would seek out wealthy aficionados that have an interest in your pursuit and preparing a well-delivered pitch to them.
The bottom line is "why would I want to invest so much money into your idea"? $500,000 is a lot of money to pretty much anyone, so you have to assert some surety of gain from this investment. They will need quantitative data... and lots of it. Stick to the facts.
Do some research to find potential investors... you will have to be diligent, but if you really feel that your idea is good (and profitable), I am sure you will take the time to find the right person (or people).
I created a hub that addresses how to make a business plan. Please feel free to use it as a reference and ask plenty of questions!
Best of luck!