Hi Trackar,
The best way is Vacation Air Canada.
We just book our second cruise and in Canadian dollar they are the one who offers the best price.
They can have you book the cruise in advance and you can wait for the airfaire ( you are not in the obligation to book your airfaire with Air Canada however the first time they gave us a very good deal). They will gave you the price for the cruise and you can book if you wish too the bus transfer (if you want or you can wait) all in Canadian dollar. You will have to give a deposit of 400 $ CAN per person. You can cancel with no penalty up to 60 days prior the cruise.