If your device is up for renewal or your looking to switch carriers, then head over to Future Shop or Best Buy. They’ve both dropped the price on the 16GB iPhone 5S to $49.99 on a two year term. All colors (Space Grey, Gold, Silver) are available.
The price will only be available for a limited time and is good for both new activations and upgrades. If you’re having problems getting the upgrade price in-store (and your account is due for an upgrade), call your carrier directly and they should be able to price match the $49.99 offering.
Best Buy and Future Shop can process activations and upgrades for Rogers, Fido, Telus, and Bell. Unfortunately MTS is not on that list.