Having done similar projects in the past, there are a few options...
Best option I have used:
http://www.stage-props-blank-guns.com/
Most of the handguns run about $100, but they have amazing realism. They have both prop guns (non firing) and blank guns (flash and sound).
I have used are to buy cheap toy guns, then paint and finish them to add realism, but in the end, they look like cheap toy guns to anybody that knows anything about guns. I do not recommend this...
Another option I have used is to disable REAL guns that I could access. Removing the firing pin from pretty much ANY gun will make it safe to use in your film. Obviously, do not use live ammunition, but make some realistic looking dummy rounds to sell the shot when your hero loads his revolver, or sticks a mag in his pistol.