Beside Sunshine Coast Australian universities, the UK (UEdinburgh, Herriot Watt, and 3 others you can choose based on various criteria including rainfall, selection tests or lack thereof, ranking for math) and the ESSEC/Centrale Bachelor’s degree, look into degrees in English outside the US. If you don’t mind the cold, Waterloo and McGill in Canada are definitely worth looking into, replacing some US universities. Thousands of students admitted to US universities in 2025 couldn’t get visa interviews or had their visa denied with no explanation.
70k is a high amount and with a merit scholarship it could really open a lot of possibilities in the US and worldwide.
In the US, Case Western Reserve would be a solid choice too, and merit could well bring costs down to budget.
Sorry, I see UCs have increased their OOS/Intl costs, but Cal Poly SLO (considered better than some UCs) should be within budget - it’s currently 60k full cost of attendance.
I suppose you could look into Penn State’s math majors (about 60k COA) - based on your record it’d be a likely admit. Schreyer would be unpredictable though (quality of essays matters most).