Yes the yellow pages are your friend, but buying the paint is the easiest part of the process. Check out http://www.autobodystore.com/cgi-bin/config.pl?index for the best auto painting discussion group on the web. And please note that auto paints are highly toxic and the painter should be using a supplied air system.
In addition to these, try www.autobodydepot.com I get all my stuff there and am more than happy with the service, prices and shipping speed. They sell everything you need to paint your ride.