When it comes to the costs of websites, they can range massively. There are even companies who will allow you to create a free website or one that is only a small monthly fee. These websites are often ok for people who just want a one- or two-page site to put on to their business cards but they are often very restrictive in terms of what you can do. They also often are not programmed in the best way for SEO (Search Engine Optimisation) which means you may struggle to get the site ranked highly on the search engines such as Google.
You may get hugely different quotes from different companies, especially if the website is quite complex. This may be due to their pricing but it could also mean that they may have misunderstood the brief. Be sure to explain in as much detail as possible what you need the site to do and how you want it to look as the more detail you can give the more accurate the price is likely to be. If you do go for a really low cost site you need to bear in mind that it may have been built using a template that many other websites also share so you are likely to find other sites that look the same.