There are 2.2 billion internet users in the world (find this statistic and more at Internet World Statistics). To reach an equivalent audience by other marketing means would be staggeringly expensive compared to the set-up and running costs of web site.
Business is worldwide but your office hours are not. A web site serves your customers 24 hours a day, 7 days a week without adding further running costs to your business.
A web site is the easiest and most cost effective method of getting a foothold into the international marketplace.
With a web site you can open up discussions with international markets just as easily as the business across the street. But remember the same can be said of your international competitors. Don't get left behind. Don't let others steal the clients from underneath your nose because you are not visible on the web.
Back to benefits of a web site