The "cloud provider rates" for this are a bit crazy. It's great bunny.net is offering a (more flexible!) product basically for free.

The NTP Pool does ~1m dns queries a second on the hourly peak with a small-ish (old) Go program (called `geodns`) running on a bunch of mostly small VMs around the world. The average is much less, but paying $0.70/million for ~11 billion queries a day would be a lot of money for a "random volunteers on the internet" project at "cloud provider rates".