I just priced my July trip with Westjet.....$650 per person from YYZ. It's only $300 per person from BUF....and I thought that was high.BUF is only and extra hour in the car so I would say that's more than worthwhile on a $1400 savings.
Allegiant has some cheap fares as well from Niagara Falls to Orlando/Sanford airport. Depending on dates in July I see return fares inc taxes for $146.58. Take carry on luggage and get seats together at the airport so no extra fees.