Why can some designers make a site for only a few hundred dollars?
There is a lot of work that goes on under the hood of a website, so if you're getting a website for only a few hundred dollars then there will be important steps missed, or the designer is inexperienced and doesn't know about them.
Look at the question 'Why does it cost so much for a website? I can make one myself using popular hosting companies "Site Builder" software!' and see the standard steps involved to provide a professional looking & functioning site. To complete this amount of work for only a few hundred dollars would mean your designer is working for less than the person scanning your item at the Coles checkout. Should you let that person design and take charge of one of your more important marketing tools for your business?