Identity Design

I'm just thinking about starting my own small business. I was considering online web site builder to create page that will represent stuff that I'm doing but so many people tell me that it could be extremely profitable on this step to think about foundation of brand. According to the information based on my research, there's design agencies that create identity design. All the visual's that represent a company including web sites. My question is, is it reasonable to use this service now? There's a meaning that it could increase future sales. Thank you.