| Cheap Flights: San Antonio or Austin to/from Montreal $257-$288 r/t â American / United American Airlines and United have round-trip flights from San Antonio or Austin (SAT/AUS) to Montreal (YUL) for $257-$288 with a connection. Flights January to April, and also September. No Friday departures. Note: Carry-on bag is allowed for free on American Airlines and United. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate. We donât charge a subscription fee. All of our deal notifications are available for FREE via Instagram, Facebook, Twitter, our Webpage, and our E-mail list. If you are paying someone a subscription fee for our content, you are being ripped off. Read More Cheap Flights: San Antonio or Austin to/from Montreal $257-$288 r/t â American / United . | 