TAS is actually 1m per year once you add up all costs. That’s 83k per month.
https://www.tas.edu.tw/admissions/tuition-fees
Dominican is 450k per year (37k per month). Still outside of OPs budget. Unfortunately that seems to be the cheapest international school in Taipei.
http://www.dishs.tp.edu.tw/admission/schedule-of-fees.html
As for bilingual (not international) schools, this thread has a good list with their fees:
1 Like