Car-part.com. I've bought 2 or 3 rads from the JY about $75 each or so. I also bought a rad off a member here for about $60 iirc. Look around maybe put a post in the FS/WTB area? I don't know about OEM/stock replacements from other cars... You can buy a nice aftermarket Koyo for between $300 to $400 so don't go spending that kind of cash on stock garbage.
edit: well these are US $ prices. Dunno how well car-part.com will work for you in Canada
I know there are zilvians up there tho maybe try the WTB area...