The Software-as-a-Service (SaaS) revolution allows companies to subscribe to software applications and outsource operating the back-end infrastructure to the SaaS vendor. In most cases, the SaaS vendor can do this much more cost effective; providing overall cost savings for the company. As a result, companies can spread their IT budget across many more applications to support and grow their business operations which will in turn contribute to the bottom line.
Here is a great White Paper on Saving Money with SaaS. See https://www.givainc.com/wp/save-money-software-as-a-service-saas.cfm