There are 2 costs involved, the domain and the web hosting.
The domain costs around $10 per year and I already paid for it for the first year.
Web hosting costs around $50 – $100 per year, however in my sale, I offer 1 year of free web hosting for all websites. If you want your own web hosting account, I can recommend HostGator with their 3 years plan for unlimited domains, where you get up to 65% off [Direct Link]. I have been with HostGator for over 7 years now and I can honestly say that I recommend them. I have even written an in-depth review about HostGator on my blog.