Check out Porter Airlines. It's a Canadian charter airline servicing the east coast. One way flights Boston to Montreal are about $100 right now, with a brief layover in Toronto(my hometown). Fares might be a bit higher by 2014, but not by much. It would get you to Montreal in just a few hours. That's what we will be doing...Toronto to Montreal, then afterwards Boston to Toronto. Faster than the train and about the same price. Though a train ride in June would be quite beautiful...
Anyway, good luck!
Cindy