Something to consider is that speech therapy is generally a broad topic and therapists will treat a variety of conditions. It is worth asking what experience they have treating stuttering. Look around for other therapists, support groups or classes to determine if $120 is a fair price. I paid £259 for a week long intensive speech course in London. The centre I went to is subsidised which explains the cheap cost. I paid £44 a session for speech therapy. I have seen some places charge up to £100 which is similar to what is being asked of you.