I believe J. Malcolm Wild (J.M.W. Clocks) carries the real thing.
They are not listed on his website which only shows a sample of his merchandise but his catalogue lists the item as JMW-705 "Bulls Foot File". The very clear photo shows it uses a fine cut metal diamond pattern rather than a diamond coating.
Mr. Wild caters to serious clockmakers, antique restorers and model engineers. He carries a lot of really good tools.
Has anyone ever tried using an endmill instead of a Bulls Foot file?