I think it is important to note that you can use third party domain registrars to purchase your domains and still manage them within Route 53. All you will need to do is create your hosted zone on Route 53, verify the name servers used in the details and change the name servers on your domain registrar to the ones listed on Route 53. You can also purchase domains from AWS as well, main point being your domain registrar and your DNS service provider can be two different entities.