If Daniel Carr got his hands on one, there would be a whole new generation of 21st century 'ancients' available for purchase
Here is a recent one from a Leu Numismatic auction, it sold for 16k Basil I the Macedonian, with Constantine, 867-886. Coin Die for a Solidus Reverse (Iron, 23x33x25 mm, 105.92 g), Constantinopolis, circa 871-886. bASILIOS ЄT COҺSTAҺT' AЧGG b' Crowned facing busts of Basil, with short beard and loros, and Constantine, beardless and wearing chlamys; holding patriarchal cross between them. Cf. DOC 2 and SB 1704 (for solidus). Unpublished and unique, the second known Byzantine coin die and the first of a solidus. Somewhat corroded and rusty, otherwise, very fine. ( From LN Catalog)The discovery of a new Byzantine coin die is, to say the least, very exciting. Throughout history, mints have carefully guarded their dies from being lost or stolen, for obvious reasons, which is why only very few ancient coin dies have escaped destruction and survived. While a reasonable number of Roman dies have emerged over the years, only a single Byzantine coin die had been known up until now - it was a die for a bronze follis of Justin I (518-527) from Nicomedia, offered for sale in Triton V, 16 January 2002, 2253 and in Classical Numismatic Group 105, 10 May 2017, 1029. Our example, an iron die for the reverse of a solidus of Basil I with Constantine, therefore is the second Byzantine coin die known - the first of a solidus - and as such of the highest numismatic interest and importance.
Here is the one I was talking about earlier. http://www.forumancientcoins.com/numiswiki/view.asp?key=Tiberian Coin Die I went searching and found several others. I don’t know if they are all genuine, though.