The market for high-end graphics cards used to work like the market for almost any other piece of computer gear. You’d go to your local electronics store, pick one up off the shelf, and pay an amount right around the manufacturer’s suggested retail price.

But the rise of cryptocurrency mining has created an unprecedented global shortage of graphics cards. If you go to your local retailer, you’re likely to find bare shelves where the beefier cards used to be. Instead of trading at a discount, used cards routinely sell for well above MSRP on sites like eBay and Craigslist.

And it’s driving PC gamers—who used to be the primary market for these cards—crazy.