Example cost breakdown
Around £250 for those who don't have time to scan this list.
This is an example of the costs involved for a simple Information Site for a small business. In this case, there are three pages of content, all supplied by the client, plus an email enquiry form. I'm using a new startup as the client so you can see associated costs if you're starting from scratch.

- Domain
If you don't already have a domain name, I'd recommend the guys I use, 1&1 Internet (link at the bottom)
£3.52/year for .co.uk - Hosting
Again, if you require basic hosting, you can get it cheap and well managed from 1&1
£2.34/month (£28.08/year) - Design
You'll talk with me about what you would like and then I go away and do it
£100 (2 hours) - Build
I take the design and the content and turn it into a website
£90 (3 hours) - Updates
To update a telephone number or rectify a typo is trivial on such a small site so would usually not be billed. Most other updates will be ammending existing information and not adding more as this can become costly if not properly planned. Most updates to this type of site will take less than an hour (my minimum charge).
£30 (1 hour) or free
Assuming you have at least one update in your first year, this comes to around £250 for your first year. Compare that to the cost a Yellow Pages advert. Subsequent years will only incurr hosting and domain registration charges (updates to your content by request) and will cost £31.60 with 1&1.
This estimate is for a typical small information site and is here only as a guide. Your website could be cheaper than this or more expensive because more work is required.
1&1 Internet for Domains and Hosting