I really like this post because the list that is linked includes a number of moderately sized colleges which are neither “bigger schools” nor pure LACs. They typically do not offer PhD’s but they do offer multiple undergrad schools, i.e. A&S, Engineering, Business, Education, Nursing, etc. Like small LACs, they are focused on undergraduate education, are student focused, and have smaller classes. The Engineering School at these colleges will tend to have the students with the highest test scores in the entire college.
I bring this up because the family budget for college is $50K per year. Since these colleges tend to have higher acceptance rates than the top LACs and the top research universities, these are where a the “tippy top” son of the OP is almost guaranteed to find merit aid.
Look past the top of the list which features the Rose-Hulmans and Harvey Mudds of the world and past the military academies. In the top 50 are some very fine undergraduate colleges which provide multiple option for their students at schools with moderately sized enrollments. Here are some examples with undergrad enrollment in parentheses:
Bucknell (3700)
San Diego (5500)
Tulsa (3300)
Gonzaga (4800)
Seattle (4300)
Bradley (4600)
Portland (3600)
Hofstra (6100)
Manhattan (3400)
TCU (9700)
Mercer (4900)
Hartford (4500)
Hope (3100)
Quinnipiac (6800)