Every business needs a domain name. We use GoDaddy for domain names but there are other registrars out there.
It is best if domain name and hosting are purchased from different companies in case you have to switch service providers.
We offer annual domain name registration starting at $15/year. Many people have us buy and manage their domain name for them through our GoDaddy account and we bundle the cost into hosting. (here's why you might want us to manage your domain name)
If you prefer, you may buy the domain name yourself. You may search using the GoDaddy or a similar site to find available names.
Tip: often RetailMeNot.com has good coupons for GoDaddy.