> running a domain costs money. there's no way around that - it requires server resources to respond to dns queries, and that requires servers and electricity.

I guarantee you I can store and make available over DNS the less than 1 KiB of data for less than a penny a year.

Instead of free, charge a flat $1, put it in long term US treasuries at 5% / TIPS at 2.5% and you’ve covered your hosting costs forever. The principle will never need to be touched.