Delphonian mega-dollar
From Tardis Wiki, the free Doctor Who reference
A Delphonian mega-dollar was a large coin from Delphon which was made from solid gold. The Fourth Doctor had some Delphonan mega-dollars on him, and used two gold coins to entice a Roman stallholder to give him more information on recent instances of sudden blindness. He later gifted another golden coin to a young slave who showed concern for his companion Sarah, and intimated that this would be enough for the young slave to buy his freedom. (PROSE: Sarah Jane and the Temple of Eyes)
