Normally, these modern coins would be worth 50 pence in the United Kingdom, about 78 US cents at current exchange rates, but they are rare due to artificially restricted mintage. The Royal Mint, like most modern mints worldwide, has fooled around with mintage quantities to make money by selling 'rare' coins to collectors. CoinQuest thinks this procedure stinks. The coins are not really 'rare,' they are simply manipulated to satisfy greed.
To enhance mint profits further, the coin comes in three composition: copper-nickel, silver, and gold.
Assigning values to coins that have artificial mintage figures is basically impossible. The market is extremely fluid due to collector whims. The best approach for finding approximate values is to look at current auctions on web sites like eBay. At the moment, these auctions look like this:
COPPER-NICKEL KEW GARDENS COINS:
worn: $30 US dollar approximate catalog value
average circulated: $40
well preserved: $50
fully uncirculated: $200
Silver and gold coins are worth more due to precious metal content. These values will most certainly change in the near future.
Be sure to understand what 'catalog value' means. Use our Important Terminology link.