So as a basic question, are you using the Net Price Calculators at these colleges to confirm affordability? That is a good habit to get into.
Anyway, I always like to direct people with an IR interest to these Foreign Policy rankings of undergraduates. A lot of the names are the “usual suspect”, but some are interesting:
One college I thought might be worth flagging for you was the University of Denver. Again you would have to check their NPC, but they do have a robust merit program as well.
Anyway, they are on these lists thanks to their excellent Korbel School:
Note their International Studies program is already very interdisciplinary:
But Denver also has a secondary major program, which makes it easier to add a second major field. And Philosophy is one of the available secondary majors:
https://bulletin.du.edu/undergraduate/undergraduateprograms/majorsandminorrequirements/
Anyway, I just thought this could be an interesting option for you to explore–again subject to affordability.