Skypark Airport Parking has coupons available for parking near the Toronto Pearson International Airport, the airport operated by GTAA, on its website SkyPark.ca. As of January 2016, these offer a low rate as well as every sixth and seventh day of parking free. Groupon also sometimes has coupons for airport parking available, although there are not currently any in the Toronto area.
AirportParkingReservations.com has a search function that shows the daily rates of different parking lots around different airports, including Toronto Pearson International Airport. As of January 2016, the website is offering a coupon code to save money on reservations made through it.
The website for Toronto Pearson International Airport, TorontoPearson.com, has a page for making reservations to park in one of the GTAA lots. As an example of a typical discount, making such a reservation may provide a discount of up to 25 percent for parking in the terminal daily park garage during certain promotional times.
BestParking.com shows parking rates around different airports, including the Toronto Pearson International Airport. Next to the map, select Toronto (YYZ) and the parking start and end dates and times. The results show the cost of parking in different lots for that period of time. Blue markers designate lots with discounted rates for booking ahead.