Sorry, I didn't realize you were in Canada. It doesn't seem like Future Shop is giving much of a discount off retail, so I'm sure you can do better on the prices elsewhere. Try starting a new thread if nobody picks up on this one asking for a good place to source discounted subs in the $200 - $300 range in Canada. I'm sure there are some members who know where to go for the best prices.
By the way, your sub was way lower quality than the rest of your system, so an upgrade was in order anyway! If nothing else, you could pic up a Bic PL200 from ebay...or if you push your budget a little you could get something from one of the ID companies.