My most poly-friendly councelling experience was with someone who when I first met her, had no idea about what polyamory was. But I talked about it, and she did a LOT of reading. She helped me tremendously go through my feelings and doubts, she challenged me to think about things and to become much more confident that what I felt was my chosen relationship configuration was not being done out of selfishness or a lack of commitment (in fact, she commented once that in some ways poly showed even *more* willingness to commit).
And she was on my health plan...
I told her of the general plight of polys to find "poly-friendly" professionals and she seemed surprised. She said that "any mental health professional worth their salt could work with this type of relationship".
I know that many haven't had this experience, and there are some horror stories out there, but if you can't find any specifically poly-friendly folk out there, give your local ones a try - have an initial session with a few, and see if any seem truly open-minded enough to be able to work with you.
Please check out The Birdcage - an open, friendly Polyamory forum for all parts of New York State
"Listen, or your tongue will make you deaf." - Native American Proverb