Same boat over here, only autism though. it's approx $1k just to try and get assested best case scenario.
I heard that if you have health insurance you can check if it can cover at least some of the cost. In general you should also check what benefits you can gain from the diagnosis :p sometimes the price is worth it, in some places I'm pretty sure that you get cheaper healthcare, pay less taxes and medical insurance and even get financial aid if you are deemed eligible. Not sure how it works without insurance if that's the case tbh