I have an Antec 1240/Cheiftec Dragon and I fit a daul 120mm core on the top. it cost me 2 CDROM bays, but I still got 4 more, so I don't mind
Anyway I got the core for $29 from Autozone. Not sure if they have them in Canada, but its just a Ford Econoline Heatercore, so it shouldn't be too hard to find.