Kennedy Krieger in Baltimore has a pediatric feeding disorders program that's supposed to be one of the finest in the country. I don't have any first-hand experience with this, though.

http://feedingdisorders.kennedykrieger.org/

I would contact Gabriele Nicolet at Speech Kids and see if she has any suggestions. She's not an ABA specialist, she's a speech and language therapist, but I've seen her work wonders with a child around food issues (although the child didn't have autism at all, but there were some serious issues that she solved 100%). So she might know people in that area who do that kind of work. She works in DC, and perhaps some in MD (not sure) but I'd use her as a resource.

speechkids.com

gabriele.nicolet@speechkids.com

hi there - might anyone know of a place/specialist somewhere in our area where i can arrange for ABA services for my son, who also has extremely restrictive food intake/selections? It was suggested that we try and find not just an ABA therapist, but also someone who has experience working with children on an extremely restrictive diet. i am north of DC, in Clarksburg, MD. many thanks in advance...