Welcome to the forum, lucky!
You don't need to get the same series of Polks for your surround speakers. Ideally, they would be...but it's not that critical for the rear speakers. Also, with modern receivers that have auto set-up routines and equalizer algorithms, matching of the rear speakers is even less important.
Does your receiver have an auto set-up system?
There are other Canadian members here that will probably give you much better input on what to get than I can. While you wait, try searching through the forum. There have been questions that have come up about where to buy gear in Canada, for example.
Adam