I just went to see my PCP this week about what I suspect is ADHD and she referred me to a psychiatrist to be assessed, but also told me the wait could be quite long so she also told me about an online assessment option. As it turns out, the psychiatrist was out of network, but the scheduling lady on the phone told me the cash/non-insurance price was $250. So you might ask about that non-insurance price (I'm sure they could do a payment plan, too even if it is more expensive if that makes it easier for you). I would have had to wait until december for the next availability, so I did the online option that my PCP recommended (adhdonline.com) and it was $180 and I'm awaiting results now.

Edit: got my results back less than 24 hours later (estimated time was 5 days) with a diagnosis of adhd and depression. They faxed the diagnosis to my PCP and now I'm going to meet with her to talk about treatment.