I've been using Cloudflare, and it has been good so far. https://www.cloudflare.com/products/registrar/
The only downside is that they don't have top-level domains that other registrars do, but it is worth checking out.
The only downside is that they don't have top-level domains that other registrars do, but it is worth checking out.
To compare a popular service, Route53 (no affiliation) limit is 10k and they won't charge extra if you want to increase the limit, all you need to do is open a support ticket explaining the use case.