The actual files of your site need to sit on a server. I can take care of it for $96au/year*, or you can choose another company to host your site. You can certainly find cheaper hosting if you’re willing to maintain your site yourself – my fee also covers setting up email accounts and any time required to fix problems.
* If you’re going to offer files or music or video for download or if your site needs a lot of space it may cost a bit more, I’ll let you know early if I suspect this.
Also if your site becomes very very popular it will cost more – every visit to your site uses some bandwidth which isn’t free, so if millions of people are visiting your site every day it will cost more to host. Thousands I can easily cope with.