Like Chris says, there are a hardcore group of collectors like even myself that like the contemporary forgeries a lot more than the genuine mint articles. Think about it, for instance I have a counterfeit coin from the reign of Mary Queen of Scots, you have to realise that the penalty even for possession of such a thing, let alone passing it unwittingly and most of all making it in the first place was simple - death. It was not a lot different in England either. Even coppers were counterfeited, but usually not given the stiffest penalty, but silver was an automatic ticket to the gallows or whatever else at hand. For that reason counterfeits, and because of the great re-coinages in Britain at the beginning of the 18th century are now quite scarce. They got much more common after the 1780's, better equipment, better economy, great coin shortage and more lax interpretation of the law.