Unless you have an incredibly high income, half of the expenses will not be half of the sticker price of college. You will fill out the Financial Aid Form, and that will calculate your family's expected contribution (In our case, it was $0).
Individual schools will offer your children a package. If the price of the college is $30K a year, usually the package will cover everything except your expected contribution, using scholarships, loans, work-study, etc. Those are the numbers you work with.
I would think that following a classical program for high school would seriously impress colleges. My son did not really follow WTM - we basically did our own thing - and he is starting in the fall at a state school on a full scholarship, covering everything including books and is in their honors program. I think it's worth it!