UCSD sets a high bar, in terms of its CogSci department!
It sounds like you have run the NPC for Northwestern and determined that the projected cost is affordable, so that’s a good sign.
If a smaller school would interest you, Vassar has the longest-established CogSci department, a great reputation, and generous aid.
Pomona has an excellent CogSci major, and Scripps students can choose this major also, as an off-campus major. It’s particularly good for students with an interest in Linguistics, since it’s a shared department, but students can also emphasize CS or other aspects of CogSci. (Philosophy, Human Centered Design, Psych, etc.)
WashU has great Cognitive Neuroscience and Psychological & Brain Sciences majors, and also this first-year “ampersand” program: Mind, Brain, and Behavior | Arts & Sciences
For a more computation-heavy CogSci major, Carnegie Mellon could be worth a look. (Historically, they have a reputation for being less generous with need-based aid, but this seems to have shifted for the better, so run the NPC and see, if you’re interested.)
Another more computational option is to do a combined major at Northeastern: CS or Data Science in a combined degree with Behavioral Neuroscience. For a less computation-heavy option, Behavioral Neuroscience + Design, or Behavioral Neuroscience + Philosophy, with the option of a Linguistics minor.
The Engineering Psychology major at Tufts has a slightly different focus, but some students who like CogSci find it appealing, and of course the regular psych major is strong too.
The URochester Brain & Cognitive Sciences department is great. Carleton is excellent too (My CogSci kid found the monkey research off-putting, but ymmv! She ended up attending Rice, which is another good option to look at.) Wesleyan has a CogSci concentration for psych majors.
If you say more about which aspects of CogSci interest you most, and what you hope to do with it… and also which programs are more or less appealing… maybe we can help narrow it down more.