Who do I talk to about getting diagnosed?

Over the past few years, I have slowly noticed myself starting to fall into more and more ADHD symptoms, and I wanted to know WHO I should actually talk to about this. Is it my primary physician, a therapist, someone else? Does anyone know of a good article or site that explains the symptoms in more detail as well? Certainly don't want to spend $250+ on a doctor's visit if I don't have to (thanks America)