Made From Scratch vs. CMS

Ok, I’m just starting to get into web design/development. I’m hoping to actually start selling sites within the next few months. The problem I am having is I’m not sure whether to make sites from scratch or use a CMS (Wordpress most likely). Would there be a problem if I was selling Wordpress sites (i.e. look unprofessional or something)? Is it better just to start from scratch, knowing that this may increase the time it takes to have a finished product?

What are your opinions? I’d like to know that way I can focus my portfolio (I’m doing some sites for local non-profit groups and such) on what I’ll actually be selling.

Thanks for your input,