How easy would it be and what would it cost for the "normal"man in the street to hire a small film crew?

I have just had a blinding idea for a series of films and it could be a real money spinner !!!!!
Any ideas as to how to go about it without giving the game up,to protect my idea until the filming is done?
Also the expense of hiring a crew so i have an idea of initial outlay?
The actors and actresses will be free.