That's fascinating – I always wondered how exactly Travis was running their Mac OS builds.

Based on MacStadium's public pricing, which is $150/month for the base model of the latest Mac Mini, this cannot be cheap for Travis, especially given they offered (past tense) Mac OS builds for free.

Not surprised to see them start charging more, but it's coming at exactly the wrong time given that GitHub (with Actions) is now offering a product that's a fair bit better, and it's still free.

MacStadium also offers some types of virtualized macOS environments, even a Kubernetes-on-Mac offering. So I'm guessing it's not all individual Mac minis running these builds... at least I hope not!