Record collectors spent more than $200m (£147m) at the online music marketplace Discogs last year, the BBC can reveal.
The site, which helps collectors find and trade rare music, sold more than 10m records - up from 8.3m in 2016.
Vinyl was the most popular format, with 7.9m sales - including a rare Beatles record that fetched $10,502 (£7,700).
The 7-inch single was one of only 250 issued with Sir Paul McCartney's name spelled incorrectly on the label as "Paul McArtney".
Discogs' success reflects a revival in the music industry's fortunes as well as the continuing consumer interest in vinyl.
However, its figures are largely hidden from official music industry statistics, because they derive from private sellers trading second-hand records.
Launched in 2000, the site was the brainchild of then-Intel programmer Kevin Lewandowski, who wanted to catalogue his collection of electronic albums.
It slowly transformed into a sort of Wikipedia for music obsessives - featuring crowd-sourced information on more than 9.8 million recordings, from major chart hits to hard-to-find obscurities.
But the platform really took off in 2007, when it added a marketplace feature that allowed users to buy and sell vinyl.
And with a business model similar to eBay or Amazon, where the site takes 8% of sales, Discogs would have generated something like $16 million (£11.7 million) in revenues last year.
The site's best-sellers list also provide a unique, outsiders' perspective on the music market.
The most popular record so far this year, for example, is a compilation album from the mysterious, short-lived 90s electro label Scopex.
More recognisable names like Tracy Chapman, Madonna, Daft Punk and Prince also feature in the Top 20.
Kendrick Lamar's Damn was the most-collected current release in the first three months of 2018, while Pink Floyd's Dark Side Of The Moon topped the catalogue charts.
And while vinyl is the most popular format amongst Discogs' users, the site also saw a 29% increase in the number of cassette sold last year - with 162,811 tapes changing hands.