It is very important for any business these days to have a website because most people go online and research on products or companies before making a purchase. If you don't have a website you are missing out alot on potential clients. Even if people don't buy your products or services online, they are likely to research online what you offer, so if you have a website people can learn more about your products and services and can share this information with their friends simply by sharing the website's url.
A website is also important because it helps you establish credibility as a business. Most people just assume that you have a website since the vast majority of businesses do, at least the vast majority of big companies do. If you don't have a website that you can refer people to, potential customers may assume you are a small company that does not take their business serious and once you establish this kind of reputation, it is going to be hard to make sales.
A website will not only give you credibility but also give the impression that your company is bigger and more successful than it may actually be.
There are various reasons why most business do not have a website and one of the reason is that they think having a website is very expensive. Truth is that a website can be built for very little money. Just a simple website that tells people about your company and your products is more than enough.