I'm going to have to get a new rad sometime soon also. I've replaced the original leaky rad with what appeared to be a really nice used one, but the used one started leaking after a while also. The top tank seems to be a common problem with these tanks. Something about the brass tanks being stamped, and that process causing some thin spots on the tank and making that weak area more prone to failure.
I don't want to have to go through this process again. I'm probably also going to swap out my water pump while I'm doing this just to avoid having to do that in the future. I like the idea of a factory rad fitting the way the engineers meant it...but I don't like the design of the tanks in the OEM unit. I've spoken with a local rad shop (the same guy who filled my AC), and he assures me that he can build me a custom tank that will fit like the OEM unit, for about the same or slightly less money. Something to consider...
FWIW, I think JP Toyota quoted me something like $450 for a new OEM 3 core rad. I think ENS in Saskatechwan might have the 4 core versions available...but I'm not sure.