Well, the top 10% in high school are probably more like the ones taking calculus AB or BC in 12th grade. Your son is probably in the top 0.0002% of math achievement to have completed calculus BC or equivalent in 9th grade.
http://automaticfulltuition.yolasite.com/
http://competitivefulltuition.yolasite.com/
http://nmfscholarships.yolasite.com/ (11th grade PSAT is the qualifier for National Merit status)
Also note that if the cost of university tuition is a concern, he may be eligible for substantial financial aid at some of the more expensive universities. Each university has a net price calculator on its web site that can be used to get a preliminary estimate of financial aid.