Our office gets cake from cake works for special events. I don't know about prices because I only eat the cake and there's no complaints in that department.
http://www.eatcake.ca/
For our daughter's second birthday, we got a two layer marble sheet cake from Sobey's decorated a la Disney's Tinker Bell. The cake looked really good and they had literally dozens of decorating options. We got the second biggest cake they sold and it came it at about $30. I would definitely consider Sobey's again for our future cake needs.