I've been searching pretty hard over the last few years for a good radiator, and the only option in the US seems to be roughly four varieties of chinese all-aluminum models. There's a company in .au that supposedly still makes a copper-brass one, but they explicitly state they will not ship overseas, and did not respond to an email asking if they'd consider changing that policy. You can get the aluminum ones on ebay, or at o'reilly if you want a warranty. Quality... varies. The o'reilly one isn't terrible. The $90 ebay special is pretty ugly. I haven't tried the "Fenix" one for a higher price. There's a couple middle-priced ebay options. When searching, look for "leone" and "brumby" radiators, since that's what the rest of the word labels them as.
If you do find a copper-brass one that's actually available in the US, let me know!