A Business Built on the Troubles of Teenagers
More and more parents of troubled teenagers are sending their children to special programs without regard to cost, and the number of private schools serving them has soared, attracting investor interest; new 'feel good' programs combine therapy for drugs and other disorders and education, often in outdoor setting, at average cost of $5,000 a month; influx of money from investors in private schools seeking high return on equity is worrying some traditionalists in field, who are concerned that bottom line may take precedence over students' needs; Aspen Education runs 31 programs for children with behavioral or other problems, making it one of largest providers of services for troubled teenagers; map; chart; photos (M)