Hi A.,
I am a speech-language pathologist. Although I now practice privately, I worked in the public school system for seven years. Does your step-child attend public school? I ask because I know that when I worked for the school district we were informed that if we recommend another institution for additional testing, the school district would have to pick up the tab. Since private schools are not held to the same regulations, this would not relate to such schools.
It is always a good idea to call several practices and find out if the rates are comparable. If they are not, you might want to find out what services set the higher cost practice apart.
Good luck! Your step-son is fortunate to have parents who are so concerned and eager to help him.
S.