It really varies.
Some web developers/designers use templates.
Some design from scratch.
So, it is a really... WIDE ball park of fees and costs.
It is not, all the same.
Then, there are free websites... that use templates.
But with any website, you also need a web Host. Hosting.
What exactly to you mean by "design" a website for you???
The graphics?
The layout?
The branding?
The logo?
Or all of those?
Then... is this an e-commerce type website? ie: shopping etc.
Or for blogs? where there is no need for a shopping "cart" on your website?
Keep in mind that designing/creating a website for someone, is real specific. Every website and every person has different needs for their website and whatever their vision is for it.
Then the Web Developer... needs to work with you on that... basically figuring out what you need/want.
There are Web Developers and Programmers, that design from scratch. Not using templates. And some do.
Also, some Website Developers... will ALSO "manage" your website for you. Unless you are a computer web Programmer... you would not know how... to troubleshoot technical problems on your website, nor how to upgrade it or tweak it or edit it, etc.
Some Designers... will do a site for you using their assorted templates. Then after that, it is hands-off. Meaning, you paid for it, then other than that... you are on your own. Or you can go back to them, if you need anything changed etc.
You also need to, have a Domain name.
And research that too.