Using guns in your independent films is risky business, and expensive to boot. Since you probably don't need to actually shoot anything, you can probably get by with a replica prop gun. If you're gonna do that, why not make it yourself? This video will show you how to make a realistic prop Glock handgun with working trigger, slide and magazine lock.
You'll need masking tape, black spray paint, scissors, utility knife (X-Acto knife), pen, hot glue gun, ruler, foam core pasteboard or cardboard, rubber band, very small pipe (or pen tube), wood stick, metal or aluminum strip, paper, printer and a spring.