The 50 Most Expensive Private High Schools In America Groton School. ... Horace Mann School. ... The Hotchkiss School. ... Riverdale Country School. ... Avenues: The World School. ... Beaver Country Day School. ... Salisbury School. Location: Salisbury, Connecticut. ... The Lawrenceville School. Location: Lawrenceville, New Jersey. More items... Oct 1, 2014