Cheapest is use a website builder. They give you a standardised templates that you can populate with content. This is a quick fix for your business. It will give you an online presence while you get your business up and running. Note to remember: such builders can be restrictive and not necessarily easy to use.
Employ a freelancer who can help you develop your website and manage the process yourself.
Get everything under one roof. An agency who will design, build and manage the complete process. This is the preferred option – handing your project over to experienced professionals.