This trip I booked my own airfare. I watched the airfare prices weekly. One day the prices were really low and great, as soon as I booked mine though the price went back to the normal price.
I purchased my tickets through Undercovertourist through the mousesavers discount. (subscribe to the newsletter to get this link it comes out on the 15th of the month).
I actually used 2 different TA for my trip, one for the land and one for sea (only because it was a group trip and I had to).
I would recommend either of them. They are both online companies and you mainly communicate via email, but you can talk by phone if you wish. One is of course dreams.
You can use any TA in Canada, but do your research first as they don't always know the best choices. Dreams and the other TA I use both will watch your reservation for better deals so if the price goes down you will save.
I hope I was a little helpful to you. Our biggest expense was our airfare.