As your business grows your website needs to be able to grow to handle more traffic and still get good performance. This is called scalability in technical circles. Your web hosting solution must be scalable. Your web hosting provider must be able to offer you upgrades to larger bandwidth, better servers and even dedicated servers for your company.
Tip: With the cheaper options you will be on a server that is shared amongst a number of websites, This is usually fine for startups. But as your business goes you may want to eventually plan to have your own server.