Saving $2500/year @ 10% compounded annually over 18 years is a little over $120K.
Not qualifying for financial aid, the total cost (tuition, room, books) per year @ Stanford will run you $50-60K--easily $200K+ for four years.
If this tuition history chart (http://www.collegecalc.org/colleges/california/stanford-univ...) is any indication of the future, four years at Stanford or any prestigious college in 2032 will set you back a ~half million USD!
I suppose the parents can bet on the smarter of the two kids...