+1. YYZ is by far my most common destination, and definitely one of the most expensive to fly to. I've looked at the BUF and drive option as well, but can't see how it really saves anything once paying for car and fuel (even though I rent a car in YYZ anyway - still doesn't save enough to be worth it).

I don't know DSM at all, but I can confirm that a trip to YYZ will set you back more than you think it should no matter how you get there (that I've researched anyway). Sorry!