It all depends on how much you need out of a website and how skills your designer is. Heck, even location can make a difference in how much you need to pay. On average, a website designer will cost $75 per hour to hire. 

However, that's the average. The vast majority of web designers will charge between $27 to $100 per hour. On the lower end of the spectrum are designers who often hail from developing countries or who are just starting out. On the higher end of the spectrum are people who have made a name for themselves in web design and also act as developers.