Considering the Demographics may be Reed should be considered as well. It will surely have one of the highest PhDs per capita. Kalamazoo has great chemistry program also.
20K USD for internationals will be hard to achieve except for some southern state schools like Alabama or Need blind schools where they consider your need to be similar to what you feel your need is.
Other mid-ranked need aware schools one may be able to achieve @25K with some post offer negotiation.
PS. I am not surprised with PhDs per capita of CoW. They have a great Chemistry/Biochemistry department. Lots of opportunities for doing non-trivial undergraduate research early in your academic journey. Fair number of students go to top tier graduate schools from there. My son’s friend just went to MIT.