Like Brian has said, used ones are a bit of a risk, but I had a saved search on Ebay for months, and eventually struck lucky. The add said that the radiator had been bought new, and used for just a couple of weeks. I did approach with deep skepticism, but photos, more contact with the seller meant it made sense, and I took the plunge. £325 for a 2 week old rad was too good to miss, and having received the rad, I absolutely believe that it had been used for a very short time. It has transformed the way the bike behaves in traffic.
If you start looking now, maybe you can also get lucky.