js.org VS Raw-Domain-Extension-Price

js.org, the Organization that hosts free subdomains on the js.org Domain, use a JSON/JavaScript file to keep track of all subdomains hosted under that domain. Again, people can ask for their subdomains to be added through PRs, and the maintainers get to use the PR approval process to verify the contribution and decide on whether to add or not: https://github.com/js-org/js.org/blob/master/cnames_active.js

js.org PR here. When that merges, the docs site should be back

Cloudflare offers low/no markup domain name registration with a free DNS service. This will virtually always be your cheapest option for domain name renewals. They don't list prices for all TLDs upfront, so use this list to get your best estimate.

EDIT: re-reading your message, it sounds kind of like you tried to add a domain to Cloudflare that someone else already owns (if nobody owned it then the induction process would have rejected it). If you want to register a NEW domain via Cloudflare, you need to go to Domain Registration -> Register Domains and then do some searches until you find an available domain that you actually want. It will notify you if the domain is already owned by someone else & suggest alternative names. Note that the price will be determined solely by the domain's TLD. Cloudflare doesn't publish a full price list but there's an unofficial list at https://github.com/rizdaprasetya/Raw-Domain-Extension-Price