We have not reached that juncture, yet, but I have a feeling that there are a lot of unscrupulous businesses in this field, so I don't blame you for trying to get a recommendation and for trying to find something that is not ridiculously expensive.
I would not be surprised if the most legitimate sources are free or have some kind of sliding scale fee, as I think a bona fide organization designed for helping people on the spectrum as opposed to being designed to maximize profit would have a better success rate then a predatory company. (I am not saying they all are predatory, but they give me a sketchy vibe)
If you can't find any recommendations here, I would suggest looking at local organizations where you live ( either for autism or disabilities in general ) for guidance. They may have some very good knowledge of what assistance is available in your area.