Housing carries most of the weight in any cost-of-living comparison, and a lower entry price changes the affordability math directly: a smaller mortgage means a smaller monthly payment and an easier qualifying test at the same income, everything else held equal.
A lower purchase price does not automatically mean a lower total cost of ownership, though. Property tax, home insurance and heating still apply to the specific house, and an older home can carry higher running costs than its lower purchase price suggests.
Whether Saskatoon is expensive for you depends on the specific property and your own finances, not a national ranking. Get your hand-reviewed valuation from Joel Dyck.