When I started out self employed, I built my own, small, simple website, which cost basically nothing but a few hours of my time to research. It generated a lot of new clients. Not because it was flash/fancy, but because few businesses had websites back then (1999/2000).
I decided to upgrade and had a professional one created for around £150 per month. Very professional looking, but a massive drop in visitor numbers and new clients generated from it, so I pulled the plug after a couple of years. Heaven knows what they did wrong, it all looked OK, and I checked the "meta's" etc which seemed fine, but it tanked in the google rankings.
Then I did my own again, and managed to google for all kinds of tricks to get it back towards the top of Google searches. Again, cost nothing but a few hours of my time.
For the past decade or so, I've been using a small local one man band who charges £299 per year to include hosting, occasional tweaks to the pages, etc., and have been generally happy with google rankings, viewings and new business generated.
I think it depends more on the quality/abilities of the web designer rather than price. As above, the most expensive one I paid for produced very poor results despite it looking good and apparently fully functional.