There exist very accurate tests for autism, but /getting/ a diagnosis can be difficult. A teacher spotted autistic symptoms in me back when I was ten and recommended I get tested. It wasn't until three years later that a couple thousand dollars got taken out of my college fund and I received a day's trial of tests to determine that I have it. Insurance did not cover the procedure.

Now-a-days, people have more understanding and awareness (this was a little over ten years ago), but it is still an expensive procedure, involving many specialists of different areas, sometimes neurologists and brain scans.