Having a hotel that is on the grounds of the airport and has access to Pearson's people mover is extremely convenient. But the convenience comes at a price.

You can search for hotels with a free airport shuttle service. And restrict your search either on a map or by distance from the airport proper, depending on the search engine. I would also advise searching the reviews for those facilities/amenities you care about (for me it is the breakfast buffet and the frequency/reliability of the airport shuttle),

I've personally used the Holiday Inn that is about 1km from the airport and depending on the date, get it for about 60% - 70% of the cost of the airport hotel. But I am a lifetime platinum ambassador with IHG and I get a lot of perks when I stay at an IHG property. I stay there because the breakfast is good, the shuttle is reliable and there is a Ruth Christ's Steakhouse within walking distance of the hotel. So I know I'll get a decent dinner as well. But these are my interests and I'm sure yours may e different.