I essentially am a freelancer. I'm a 1 man business, and i'm net 30. That being said, flat fee projects are something I do, and when i'm billing a flat fee, usually there is a 1/2 upon starting the project, and 1/2 when deliverables are.... delivered. i've only had a few clients not pay up within their 30 day window.... which for a small guy like myself is not fun.
Now, this situation you're saddled with seems to not be any fun at all. Sorry you're having bad luck with a "local".
Local, do what you said you'd do. We all in some way or anothe rhelp each other out on this site. You being all willy nilly makes it harder to trust each other.... so just be legit