The real shark move is getting a job at a university. Children of faculty and staff commonly can attend for free (and at the undergraduate level, it's a specific tax-free benefit in the tax code). Most private schools are also in consortiums so you are not limited to just your own place of employment. My son passed on the opportunity (to instead attend Illinois for engineering and club volleyball), but my daughter did her UG for free at Drake University under one of the exchanges and, after a year in Sydney, is now doing her graduate studies in Social Work at my university (though this is taxable to me).
We just got a big kick in the teeth when it comes to this. My wife works for Johns Hopkins, which offers its employees a tuition remission benefit: half of JHU's tuition - which is more than $44K this year - portable to wherever my son goes to college.
We're still in the early stages of the college search, but for now we're looking at schools with tuition in a similar range to JHU. Their websites have Net Price Calculators, which enable you to figure out how much of college you have to pay for and how much will be covered by financial aid. Most of the schools he's aspiring to don't offer merit financial aid but promise to cover your full demonstrated need - based on our income, they figure we can afford about $25-30K per year (which seems staggeringly high, but that's another story).
We had always assumed that the Hopkins tuition benefit would provide $22K of our $25-30K contribution. But it turns out most of these need-blind schools will reduce their financial aid grant, dollar-for-dollar, in the amount of any tuition remission benefit. The argument is that their financial aid grant is based on "need" and so we don't need the $22,000 that we'll get from her employer. This sucks. My wife has passed on higher paying jobs because we thought they would have netted us less than the tuition benefit.
Also, from JHU's point of view, this seems perverse. Their employee ends up realizing no gain from the benefit, as our out-of-pocket contribution would be unchanged; the beneficiary is whatever rival institution my son ends up attending, who gets to pocket the $22K of JHU's money that they would have previously extended to us as a grant.
There are options that will still allow us to take advantage of the benefit - going to a state college that costs less than $22K, for example, and it's free. Or going to a school that offers merit aid in addition to need-based aid - in that case, we would package together the merit aid plus the tuition benefit to cover most of it.
But if he gets into one of the highly selective schools, the four years of 22 thousand tax-free dollars that we'd been counting on to help pay for college are gone.
Coincidentally, the same is true at these schools for any kind of outside scholarship you earn. Let's say you're going to Princeton, and you earn a local $1,000 Rotary Club scholarship. Princeton will then reduce $1,000 from their grant to you to make up for it.