One would need to run the numbers. But it might be cheaper to pay the private school than it would be to pay for all the support that would be required.
Smaller districts around here sometimes contract with larger systems that are having to provide certain services anyway; it’s cheaper than them setting up their own programs in that area. Teacher, occupational therapist, physical therapist, aide, and pretty soon you are talking big dollars.
On the other hand, with numbers that high, perhaps they need to look at more than sticking them in trailers.
There is no problem with how NJ educates disabled kids, it works fine elsewhere. There is a problem with corruption in Lakewood. The town is mostly populated by Hasidic Jews and illegal aliens, both of whom tend to do things off the books and avoid paying taxes as much as possible. So the town has abnormally low tax revenue, but high expenses because of the large families.