Lego strikes gold with collectible minifigure

He's become the hottest ticket in town: a real-life equivalent of the golden tickets in Roald Dahl's children's classic Charlie and the Chocolate Factory.

But Lego's Mr Gold doesn't come with a lifetime's supply of chocolate. He's an inch-and-a-half tall plastic figure like any other Lego product. His value – and he has been fetching over £700 on eBay – is in his rarity. There were just 5,000 made worldwide.

The desire of adult collectors to get their hands on one is fuelling a commercial bonanza for the Danish toy maker.

Part of the success of its Minifigures range is that they come in a plastic bag so buyers don't know what they are going to get. Children can therefore trade them in the playground, adult collectors on eBay. The introduction of the limited edition "Mr Gold" into Series 10 has changed the game, however. Mr Gold is causing a stampede, with some adult collectors buying up job lots in attempt to get their hands on figure.

That can be seen in the fact that just two weeks after its launch, complete sets of 16 without the limited edition superstar can be purchased on the auction site for as little as £35.

Because of duplication, you have to buy quite a few packets to get a complete set, although canny purchasers have been known to look carefully at barcodes – or simply attempt to identify the character in the packet by feeling it – in an attempt to avoid this.

The company says it's too early to say whether Series 10 is a best seller – but adds: "Initial reports show they are off to a flying start."

The popularity is such that even the Lego shop at Westfield East in Stratford has found itself without stock on occasion, and Sainsbury's has noted a rise in sales since the launch.

But is there a flipside to this modern day gold rush? Does its popularity with Afols (Adult Fans of Lego) mean that the kids are missing out?

The company thinks not: "The reaction to Mr Gold has been phenomenal," said a company spokesperson. "It's always a fantastic coup when our consumers engage with any of our brands, so we don't view the demand and interest as having a flip side. The search for Mr Gold is a modern-day treasure hunt – something that children have enjoyed for decades. There are 5,000 Mr Golds to be found worldwide so he really is an attainable treasure. We have had 51 winners in the UK alone bag a Mr Gold Minifigure for themselves so far, which is fantastic. Children around the world are truly in with a chance of finding a bag containing this highly collectible figure."

The commercial success of the line generally can be seen in the fact that, as of last month, Lego says its Minifigures was the number one toy for the year based on unit sales, citing April figures from the market research company NPD.

And if the Afols are buying up lots of them, the kids are still getting in on the fun as well: in addition to a commercial success the product has also been a public relations goldmine, with local newspapers from around the world featuring young "winners" who've found not so much the golden ticket, but the golden packet.