Hi there,
I have to agree with the last poster.
I just moved to Toronto from Niagara and have always flown out of Buffalo. I couldn't believe how much more expensive it is in Toronto.
It is definitely worth the drive. Last year, we only paid $200 for 2 people roundtrip with Southwest.
This year, we will probably pay $500 from what we have seen so far, but using Toronto it would be $900. Again, only for 2 people.
However, if you insist on Toronto... I would recommend finding the West Jet website, or try flightcenter.ca, they have some stores around the GTA too.