Working as a web developer you encounter domains that are registered on various domain registrars. Some clients are on Google Domains, GoDaddy, Namecheap, etc. In my opinion the best registrar to use in 2017 is NameCheap.
They are a well known domain registrar founded in 2000. They made a name for them early on by allowing you to register second class TLD (.club, .info), etc. I personally use NameCheap on a daily basis, their DNS servers are fast, support is great, friendly user interface for managing your domain names. To me it’s important that a registrar provides top class security as well. I’ve turned on 2 Factor authentication (more commonly known as “2FA”) to keep my account secure. Whenever I login there is a prompt for me to enter in the 2FA code, this is sent via an SMS text message.
As I mentioned earlier the support services are great, you can contact them via live chat, support ticket or phone.
So how much does a .com domain cost? As of June 28th 2017 it costs $10.88 for a .com domain registration for one year (this also includes the free whois guard protection for 1 year).