For elementary school, I can't think of any. For high school, the Institute for Educational Advancement has scholarships and the Jack Kent Cooke Foundation might as well although JKC is another one where income is a big factor. Another thought would be if your dc are DYS eligible whether Davidson might help you out. Also, are you absolutely sure on both of your assumptions: that the school itself wouldn't give you some financial aid and that grade skipping absolutely can't be done in the public school?
I ask b/c my family isn't destitute but we also would be spending well beyond 50% of our gross income for a school with tuition like you mention and we have gotten some partial scholarships for things like summer camps. Also, grade skips are not commonly done in our district although it isn't a "never" occurance and we were approached by dd14's school regarding skipping her yrs ago, which we did. Sometimes things that aren't typically offered do get agreed to or even offered by the school when it becomes clear that the child is significantly different than the typical GT student they serve.
