I would always use a web design company, when you are not already very skilled in this field.
Because as liz2Sell already said, it is a lot more to do as just using front-page or similar programs. It has also a lot to do with combining marketing, informatics and design (usability, etc.). And all the three disciplines have a huge deepness, which can't be learned in a few months..

I came from this field and we made our website Tierralinda - Costa Rica Real Estate - Home by our own. And this was a process of 1,5 years and we are still improving.

Hope I could help a bit..