I disagree. You can find many effective good looking free website templates to start a site with or some very low cost premium off the shelf templates. If you are on a low budget I especially recommend this as your way to get a site up and running.
http://www.freewebtemplates.com/
http://www.templatesbox.com/
http://www.freewebsitetemplates.com/
When the money starts to come in consider splashing out on a custom design then.
However, if you are planning on selling high end products/services at expensive prices, then I would suggest getting a professional designer to build the site from the start. What sort of price range are your products going to sell for?
I don't think anyone has asked yet, what are you planning to sell and how many distinct products/services (
by distinct I mean that selling a red iPhone, a green iPhone and a blue iPhone is just 1 distinct product, you just offer that one product in different colours) are you planning to offer?