Probably less than you think. The best way to figure out what a particular college may really cost is to find out your child's estimated net price for that college. This is usually far lower than the published price. Your net price for a college is the published price of tuition and fees minus your gift aid and education tax benefits. Gift aid includes grants and scholarships but not loans or money earned through a work-study job.
You can use a college's net price calculator (most colleges have these on their websites) to get a customized estimate of your child’s net price for that college.