Dive into any scene where scarcity and fandom collide, and you’ll find a resale hustle lurking at the intersect. Whether it’s Wimbledon tickets or Yeezy sneakers, you can guarantee someone will be turning your passion into over-inflated profit.

Craft beer is no different. The adulation of some artisan brewers in the UK, continental Europe and the US has spawned an online grey market where hard-to-get beers are swapped like rare baseball cards or sold for cash at as much as 50 times their original sale price. For some brewers and their fans, it’s proving a headache.

A trawl through Facebook turns up dozens of beer trading groups, mostly based in the US. Some deal uniquely in single breweries – the Other Half Everything Club, for example, is solely for swapping New York-based Other Half’s beers and counts almost 7,000 members.

Here in the UK, one name regularly cropping up in trading groups is British outfit Mills Brewing.

In the tiny village of Ham on the Gloucestershire flatlands beside the River Severn, husband and wife team Gen and Jonny Mills use captured wild yeasts to coax forth a sporadic output of small-run, barrel-aged sour beers. Back in 2017, I was running my own beer store, and we had 70-odd bottles of Mills’ first ever release, Foxbic – a kind of beer / cider hybrid brewed in collaboration with genius cider maker Tom Oliver.

At about £10 a bottle, it sold out within the week. Fast forward a couple of years, and Mills has become one of the UK’s top breweries on the beer rating app Untappd – with Gen and Jonny’s brews so coveted that Foxbic fetches £500 on the secondary market. If I’d cellared my entire stock, I’d be sitting on a liquid pile worth £35,000. Which is – of course – insane.

“I think it's ridiculous – it’s a bottle of beer,” Gen tells me, stressing that the brewery pays no attention to trading or resale sites. “We have little idea of what goes on, but sometimes we’ll get told about a stupidly high resale price – and that is frustrating.

“I assume some people have missed out because of this and that's sad – we put so much time, energy, thought and love into this stuff, and want it to be consumed by those who are interested in the contents of the bottle.”

Foxbic beer from Mills Brewing.

In the US, where sheer distance and variations in licensing laws between states make legal distribution and online selling difficult, trading has been around for decades. Many craft brewers eschew distribution altogether and sell their entire output direct to the public, with queues of dedicated locals snaking around brewery car parks, sometimes waiting hours to snag what might be a limited allocation of a single six-pack.

Organising a swap with a friendly counterpart standing in line at a brewery a hundred miles away is a relatively benign way to tick a brew off your to-drink list, and the Beer Advocate website is one place to facilitate such trades. It’s hosted a trading forum since the 90s and its tens of thousands of threads reveal the almost impenetrable shorthand of abbreviations and acronyms traders employ: ISO means “in search of”; IP signifies an “in person” trade; BBA means the beer has been aged in bourbon barrels.

But in recent years, European drinkers’ obsession with New England-style IPAs brewed in the US – all drenched in juicy hops and glowing with Insta-friendly, opaque sundown pastels – has led to a boom in transatlantic trading, with beer from the Lambic brewers of Belgium’s Pajottenland region in equal demand.

Lambic is an EU-protected food name produced by just nine Belgian breweries, and its relative scarcity – coupled with quasi-mystical brewing methods involving inoculation by wild, airborne yeast – has long set aficionados’ pulses racing. Traders pouncing on Lambic produced by Brasserie Cantillon, a particularly feted Brussels brewery, led beer writer Jonny Garrett – then working for UK online retailer Beer Merchants – to pen an explosive blog titled “Cantillon is not currency”.

He told VICE: “A huge number of the Cantillon bottles we sold at Beer Merchants went straight on Instagram for trade, so we put out a post saying that no one would be able to buy it if we suspected they were going to trade it, and we policed it hard.

“We had spies in all the forums and knew the names of everyone using Cantillon to trade to America – if they placed an order, we cancelled it and emailed to explain why. My name was mud, but I didn’t care because I knew I was in the right.”

In Brussels, exasperated Cantillon boss Jean Van Roy has taken to limiting his special releases to a single box of six beers per customer – all to be ordered online and collected in person at the brewery, with proof of purchase.

“We are of course aware that online sales like this don’t completely eradicate the black market for our beer, but we feel it’s had a positive impact,” he said in a Facebook post in November. “No more solicitation in the street outside the brewery, no more customers unable to remember the names of the beers they’ve been asked to purchase, no more people buying but not drinking because they don’t like the beer.”

Sam*, 40, set up US-based website My Beer Collectibles in 2012, mainly to offload his own collection of rarities. The site snowballed, and now hosts over 1,500 secondary market sales, with Sam earning a commission from each one. Super-limited edition releases – so-called ‘whales’ in trade talk – can fetch thousands of dollars. The site’s biggest sale to date was a single bottle of US brewery Side Project’s O.W.K. imperial stout. It went for $5,000 in September.

“People come here for the simplicity,” Sam says. “With trading you have to go through the whole negotiation process, but on MBC, the price is the price. You click it, you buy it and it’s done within a matter of minutes, and you don’t have to talk to anybody.”

MBC has its critics, but Sam explains that he’s embraced by certain breweries: “They’re happy about it because it gets them out there.”

Gen Mills adds that trading isn’t necessarily all bad: “If there is no profiteering and the beer is going to someone who wants to drink it, then that's OK. When we find out that a group of people have shared one bottle of beer on the other side of the world – that's cool.”

Mike, 32, from Stoke-on-Trent, has been trading for almost three years, and says his hobby has enabled him to try hundreds of beers that would have otherwise been impossible to obtain in Britain. When we first spoke a couple of years ago, he was couriering beer out to US counterparts perhaps three times a month, labelling his packages “collectible glassware” to swerve scrutiny from customs.

In 2016, he set up the UK Beer Traders (UKBT) Facebook group, and has seen membership grow to include over 700 followers and a community in which he has found genuine friendships and travel companions. In 2018, it spawned a bottle share event, with breweries donating beers and auction money going to the Mustard Tree, a Manchester-based homeless charity.

“We’ve got a nice little network of people willing to help anybody now,” Mike says, explaining that frequent fliers to the US are regularly hauling back suitcases full of beer to share with fellow members. “Yes, we’ve got people in the group who’ll go over to Cantillon to get beer to trade – but I think on the whole they’re careful to trade with someone who actually wants to drink the beer.”

Talking to Mike, it’s clear he’s in this for his love of beer. He has zero interest in making money from his treasures, even though he clearly could: “A group of us spent about a year trading for really high value barrel-aged stouts, and then held a share at my place over a weekend,” he says. “The amount of beer was ridiculous – it was probably worth about £20,000 on the secondary market. It was dead fun!”