Based on comparisons I would say North York would be about $55 too. I found an online thing that doesn't match up with prices but it's apparently cheaper to go to 5000 Yonge vs Yonge/Bloor (where I paid about $60 inc. generous tip). Either way flat rate limos are the way to go if you can afford it. I wouldn't bother booking, because you have to then find that person, the limo area will easily find a large car to fit you all.
I know people who have used Uber with the airport. The challenge is they aren't allowed into the private areas, they'd have to go through the generic areas and be picked up like people picking up friend and family.
I'd also say be careful with Uber, I know people who paid more for Uber than a standard taxi.
TTC is $3.25 a pop at the moment with cash, I'm not aware of being able to get tokens at the airport. Just mentioning this because if you DO want to do that you need $3.25 x people in change. Or you'll be overpaying as TTC drivers do not carry change.
On the TTC the bus and onto line 2 is fairly easy (once you find the bus stop, I'm pretty sure it's the lowest level but I'm always on auto-pilot), the trek changing at Yonge would be a nightmare especially if you don't know the system. St. George is far far better as you just walk up the stairs. But that only helps if you're going up to Downsview which to my mind isn't really North York compared to say... Finch.
And just to mention it ... The Union Pearson express gets you into Union station from where you could choose if you go up to Downsview or North Finch, I would personally not recommend this because aside from probably not saving much money Union station is a complete maze.
) Also, you have it with you at least one day and you can go shopping.
