The funniest thing about this Throne is that it probably never existed. Thrones in medieval times tended to look a little more like this. Ironically, the only reference I see to chairs that look like this are from sites selling props for movies and weddings, furniture stores, or companies selling bad stock photos.
All that said, perception is reality, so if everyone wants to think these are authentic throne seats from medieval castles, who am I to argue?
If you want a "real" Throne chair, your best bet is this replica by Design Toscano, one of the top creators of historical replicas. It'll cost you only $2,600, a fraction of what some medieval monarch would have paid.