We buy pretty much all our WDW tickets from
Undercover Tourist https://www.undercovertourist.com/
They are safe, fast, ship free to Canada. The prices you see on the website are all inclusive (taxes too), keep it in mind when comparison shopping.
Note that almost all cards do charge a 2.5%ish rate on foreign exchange. Also note that all major banks charge a 2.5%ish rate at the counter on foreign exchange. In most circumstances it is really a wash; they'll get you one way or another. We use the Rogers card for US shopping, it charges a 2.5% exchange, but offers a whopping 4% credit back that offsets that rate plus more.