Why do I need it?
Will I ever use it?!?
The answer becomes pretty simple, ask yourself the following:
1. Why are you writing this blog? Are you writing it as a fun piece so that your friends and family can follow your life?
2. Are you trying to reach a large audience? If you are, then you should buy your domain!
If you can, it is easier to purchase your domain from your blog site. If you are looking for a place to buy a domain, I recommend GoDaddy, because they are the largest and they can help you link your domain to your blog with ease!