Some fundamental concepts before you begin
Domain names can not actually be purchased. You can however reserve the right to use a domain name. Essentially it works more like a rental than a purchase.
The registration of domain names is done through a registration bureau or a registrar. There are hundreds around the world supervised by the Icann and it is a lucrative and highly competitive business.You will find here a list of the bigger registrars.
In such an environment it will be a challenge to choose a service provider that will understand your needs and be able to satisfy your requests. This can be especially true because managing a domain can be complex and technical even for seasoned veterans.
We have compared and evaluated the individual bids of these services and have chosen three of them. We feel they are best able to meet your expectations because they keep the process of reserving and managing a domain name as simple as possible or propose specific services.
Note: SimpleDifferent can't host your domain name's mailboxes (e.g. firstname.lastname@example.org). If you wish to use such an address, you would need to find a registrar offering mail service in addition to domain name registration, like gandi.net.