You can look at the various cards on NewEgg Canada (www.newegg.ca), then you can check if you don't find lower prices elsewhere using www.shopbot.ca.
What exactly are your current system spec? Might have reach the end of it's useful life. And BTW, the latest WoW expansion does require a decent graphic card because of various graphical improvements.
Before buying a new card, post again telling us what you found and for what price ... because it might be a better investment to change something else or your entire PC for that matter.