If you are going to meet someone to pay for and pick up an item you found on craigslist.org, you should always use a Safe Trade Station.
Safe Trade Stations are located at your local police stations, they are either in the parking lot where they are under video survelance or located in the station it's self.
Some but not all police stations will even run a check of the serial number of what you are purchasing to see if it is stolen or not.