There is a show comming up in April in TO, if you could make it down, you could meet a bunch of great dogs and the breeders behind them. The info on the event is on the CKC web site, as well as the RCC (Rottweiler club canada) web site. I think it would be a great place to start. There is a booster show happening in your town in May, if you can wait that long!
There are a bunch of woundefull breeders here in southern Ontario, I don't see why you should really have to look any further.
Good Luck, and if you do make it down to the show, you will be able to meet some of the people from here too!!
Have you considered a rescue also? There are a lot of great dogs in need of homes there as well. Just a thought.