Whenever a new coin is launched, it's a big event for collectors - and in the case of the new 12-sided £1, there's one version that's selling for up to £950.
More than 200,000 trial coins were produced by the Royal Mint before the launch of the coin in March, to help supermarket chains, banks and the operators of vending machines get ready for its coin's introduction.
See also: Is your new £1 coin worth £3,000?
And while they're not considered rare, they are fetching very high prices.
One trial £1 coin sold for £950 in August, while another made £600 earlier this week. And a third is currently up for sale on the auction website for a staggering £1,250, with eight people 'watching' the auction.
And they aren't even legal tender.
"They are most certainly an interesting piece for anyone to have in their collection, but they are not as scarce as some of the recent reports and eBay listings suggest," says Yasmin Britton of coin-collecting website ChangeChecker.
"To put this into perspective, in 1994, The Royal Mint issued 4,500 packs of trial £2 coins. These packs can now sell for around £150 due to their scarcity."
Some new £1 coins are worth even more. Back in July, the Royal Mint confirmed that a certain number of new £1 coins had been stamped on one side with 2016 - but 2017 on the edge of the reverse.
While most were withdrawn before being circulated, at least one slipped out - and has been valued at £3,000.
Other valuable new £1 coins include one error coin with a round raised lip around the edge of the coin and another known as the 'leaked egg' error, because part of the silver in the middle has leaked into the gold.
The first run of new £1 coins feature Jane Austen, Sir Isaac Newton and The Royal Flying Corps. However, other versions will follow - and could become as collectible as some of the rare 50p pieces that can now sell for hundreds.