I went through this debate a little while ago when I still had a Land Cruiser

. I was thinking about putting another "good" used one, but it's a little bit of work to re and re the rad, and we all know it takes forever to properly burp the cooling system to get rid of all the air.
So, in the end, I purchased a brand new 4-core radiator from Toyota in Langley. After taxes it came to just about five bills in Canuckian bucks, but I thought it was worth it not to have to worry about that major component that keeps your engine happy for another 16 years...although I ended up selling the truck shortly after that

.
There was also a fairly new OEM thermostat already installed, and I immediately noticed that the water temp gauge needle was sitting a little bit lower at operating temps than it used to. Also, when I pushed my engine harder, it took a little longer for the needle to creep up a little, and it was faster at cooling off afterwards.
IMO, the stamped brass tanks that Toyota uses in their OEM rads are prone to pinholes forming because the die creates thin spots on the raised areas during the stamping process. In my old rad(s), the corrossion, cracking and leaks occured in precisely these areas. Even if you re-cored the old rad, you would still have to address these issues in the future...and your initial monetary savings will be gone along with your precious time and efforts.
Personally, if I had to do it again, I would still just buy a brand new OEM rad from Toyota. My 2 cents.