http://www.greatschools.net/cgi-bin/showarticlefeature/ca/197
Private schools cost money. Private schools do not receive tax revenues, but instead are funded through tuition, fundraising, donations and private grants. According to the National Association of Independent Schools (NAIS), the median tuition for their member private day schools in 2005-2006 in the United States was close to $14,000 for grades 1 to 3, $15,000 for grades 6 to 8 and $16,600 for grades 9 to 12. The median tuition for their member boarding schools was close to $29,000 for grades 1 to 3, $32,000 for grades 6 to 12. Note that of the 28,384 private schools in the United States, about 1,058 are affiliated with NAIS. The Digest of Education Statistics 2005 from the National Center for Education Statistics (NCES) reports that for the 1999-2000 school year, the average private school tuition was about $4,700.
Parochial schools generally charge less. According to the National Catholic Educational Association, in their annual statistical report in 2005-2006, the average elementary school tuition for Catholic schools (in 2005) was $2,607; the average freshman tuition (for 2002-2003) was $5,870. Catholic Schools enroll more students (49%) than any other segment of private schools.