This tells me that the budget is $100k for your son’s college, perhaps a bit more if you were planning of paying out of your current expenses. Just because your daughter may not be as academically ambitious does not mean that she may not want or need to have the same flexibility in choosing a college that a $100k budget would offer. Providing uneven opportunities, especially if you have indicated to both children their expected college budgets, can lead to a lot of family strife.
Kalamazoo falls within the budget. Oberlin most definitely does not. It’s as though you’re looking at rings and one is pretty but there’s a different one that’s bigger and shinier but double your budget. You might like the bigger and shinier one, but if you can’t afford it, you get the pretty one that’s within your price range.
It sounds as though you might want to investigate Michigan State and its honors program some more. There are often some very nice perks with an honors college like a nice dorm, priority registration, special programs, etc. I would at least learn more about it before nixing the university from your list.
If you’re debating about Kalamazoo since it’s in his hometown, you may want to read this thread: Going to college in one's own hometown?
Also, your son doesn’t need to decide until May 1 and he still has responses pending from several colleges. Wait and see how everything shakes out in the end.