I've done web development for years, and you learn that a) working on larger projects to always use a service like Escrow.
That way both parties are safeguarded.
The funds are securely acquired, and the people doing the work, have recourse, if the payor isn't following through with payment.
Check out
www.escrow.com
Plus if your going to outsource to a freelancer, many of those sites offer escrow services as a built in peice to their offering.