Publicists do have several professional organizations that they can subscribe to. I would recommend that when you shop for a publicist you select one that belongs to a professional organization that requires adherence to a code of ethics for membership. This protects you from scammers and fly-by-night hawkers.
Two good professional organizations for publicists are:
The cost of a Publicist is custom designed for your needs and budget. You will need to contact one to arrive at a price.
A good list of what a comprehensive publicity campaign can include is located on the Smith Publicity Company site at http://www.smithpublicity.com/?page=pubservices