Try these specialized search sites

The Behavior Analyst Certification Board, Inc. is a nonprofit 501(c) (3) corporation established to develop, promote, and implement a voluntary international certification program for behavior analyst practitioners. The BACB credentials and provides Board Certification to Behavior Analyst (BCBA) and Associate Behavior Analyst (BCABA). To find a professional near you, visit the BACB website and click on Certificant Registry.

Rescue Angels are parent volunteers of Generation Rescue willing to share their time and knowledge with others interested in biomedical treatment for individuals on the autism spectrum. Treating your child requires the care of a qualified health care professional, and Rescue Angels may be able to provide you with local recommendations based on their own experience. Go to www.generationrescue.org to find Rescue Angels located in your state. 

HelpPro, Inc. was founded in 1995 to improve the public's access to the services of mental health clinicians and organizations.Their Therapist Finder carefully identifies users’ needs and interests and matches these with our therapists’ capabilities. They have further specialized and added a search for those looking for autism-related professionals. Go to http://www.helppro.com/ASD/BasicSearch.aspx