For the truly frugal student, I would probably recommend something like what I did: take community college or AP classes aplenty in your senior year. Go straight to a college that has the best program for your interests (keeping in mind your interests may change). Graduating in three years is easy enough if you have a semester’s worth of transfer credits for gen eds, and classes like calculus and linear algebra in particular are really easy to cover before you go to college. Administration will probably try to make graduating early as hard as possible, but they really won’t be able to stop you if you have the credits already.