Those are some beautiful coins you got there! I've been expanding my horizons beyond my regular 5 or 10 oz bars that I usually buy for cheap price over spot and have been adding some coins to my collection.
There's definitely intrinsic value to some pieces like this and not just the spot price value of the silver content in them.
All these coins were bought with some premiums. These premiums depend on the price RCM charged and the general interest of the collectors. Royal family has many collectors.