The school boundaries are a bit mixed up in Arlington Heights. A St. James student could graduate and go to Prospect High School, Hersey High School or to St. Viators, a boys and girls Catholic education school. Make sure that when you talk to the High School, you tell them your address. I knew a previous client who was 1 or 2 houses away from the border of one school to another. So be specific with your phone calls to the schools. That's my advice.
I have heard recently that there are scholorships to St. Viators for families looking for a break with the tuition, as you will find at St. James School. It's worth exploring all your options.