Hi
First off, you'll need a domain name. If you're in the UK, a .co.uk domain can be as little as around �8.00, or less, for two years.
Then you'll need somewhere to host your site. Once you've purchased your domain name, that can be redirected to you ISP's webspace, if you have any, or sites such as www.sitesled.com offer ad-free hosting. Or your can purchase hosting from a hosting company, costs dependent on the traffic and space that you expect.
If you've not written a website before, and you want a professional image, then it's better to have someone to do it for you. Expect a lot of questions, requests for photographs, etc. I author websites (no, it's not an advert), and sometimes clients have no idea of what they want, so need someone to advise them.
If you want to recieve orders on-line, then the costs can increase.
Hope this helps.