“That’s not to say that it’s inexpensive to educate non-disabled kids… but it’s not $20K either.”
Just looked up per student expenses in NYC. As of 2014 the average cost per student in NYC was $18,623. But for special ed students it was $45,796 per student. For non-special ed students overall it was $15,039 and at Bronx High School of Science, one of the best high schools in the United States, it was $12,315.