Welcome to FT and congrats on the marriage! ^

You should benchmark your fares by just using AC.com. Once you know that price, you can start searching for fares ex ORD or EWR. (AC or Porter will get you to these hubs for minimal cost.)

As pointed out above, you can also check for fares ex BUF. Greyhound has an airport bus that leaves from somewhere in downtown YYZ (I'm not sure if it's the Elizabeth St bus terminal or not for this one) or you can of course just drive there yourself.

Edit:
I just remembered that there's a decent sale on right now with AC. (T/T+ fares only.) Check it out as the cheapest solution may actually be the simplest one!