Ok, why is it so expensive to find flights for less than 400$ to Toronto (from Austin).. One can travel half way round the world for than, but not hop across the border ??

Tried one way fares, skyscanner, yapta, aus-buf-yyz, no way I slice or dice it, I can get it to work less than US$ 425 ..and direct flight good lord $630..

any one can crack this one ?