@JaneorEleven
It's the same site - The Royal Mint. That "company" makes all the coins ( and I assume the bank notes? - No it's not I just checked it ) that we use as currency in the UK. I think it's both a private company for profit, but it makes the money for the United KIngdom. That website is sort of the gifty / investment side of the company. The point I'm making is it's not any old company knocking out collectible coins, those coins are legal tender in the UK. You'd be mad to spend them, and shop staff might be confused by them, but they are UK legal tender I think. A 50p coin is half a GB Pound £, sort of equivalent to 2 quarters in a single coin.
The website is a bit crap to navigate.
e.g. here's another link with all four coins as a collection
www.royalmint.com/shop/limited-editions/harry-potter/harry-potter-coin-collection/
The four coin collection that costs £20. Is one of each design of 50p piece. So has a £2 value as currency.
The four coin collection that costs £69.50 PER COIN Is the same four coins as above but made from 92.5%pure Sterling Silver instead of the usual crap metals our coins are made from. Interestingly of the 4 coins two bear the head of our Queen who passed last year, and two bear the head of our new King who is due to be coronated ( official King making ceremony ) this year. Limited to 15000 sets.
The four coin collection that costs £99.50 PER COIN "One Ounce Silver Proof Four-Coin Collection" are bigger coins with more edges are £2 coins each ( not 50ps like above ) made from 99.9%pure Fine Silver and each weigh almost 4 times what the 50p silver coins weigh. Again Limited to 15000 sets.
The more expensive coins each come in a fancy little presentation box.
For a child who grows up on Harry Potter I think those coins could be a rather magical gift. Note the coins if you buy them don't all arive in a single packet. They are yet to be released and wil be sent out one by one as they are released.