Oh, and I just remembered:
Big merit scholarships to Ivy-equivalents are almost impossible to get and Ivies don’t offer them, but
Duke has some (that are insanely tough to get). WashU, Vandy, and USC also have them (and would be easier to get but still very difficult).
JHU has two full-tuition scholarships a year for their engineering school.
Olin and Cooper Union offer automatic half-tuition scholarships.
Rice’s list price is slightly lower than other Ivies/equivalents and it’s possible he could get enough AP credits to graduate in 3 years from there. They also offer big scholarships to their top admits.
Finally, if he is open to it and went somewhere cheap/free the first 2 years:
Vandy also has (last I checked) a considerably higher admit rate for transfers than straight from HS and both USC and NYU take in a ton of transfers (not easy to transfer in to these schools but not near Ivy-difficulty either).
Or if he went somewhere cheap/free but still wants a fancy elite private school degree and/or better recruiting opportunities, he could look in to Master’s programs (only 1/2 years of costs vs. 4).
And of course, any American STEM PhD program worth attending is funded (obviously requires doing stellar in undergrad).