I like the don't go into debt more than you earn rule of thumb.
I'm not sure what is considered "normal" for International PhD admits, but I received an offer from a humanities department at the University of Toronto. They offered five years of tuition, healthcare, a 15k stipend, an assistantship, and entry into a competitive scholarship that would be worth an additional 4-5k per year.
I don't think that you should have to pay tuition for a PhD program, but it probably depends on what offers you get. If you hear from other universities, you may want to try and negotiate.