Then it is portable to several platforms. That aspect alone can save thousands of dollars every month to an organization. With regard to software, not only you will find almost every type of software you may need for free or very inexpensively, but bugs are corrected and new features are added with incredible agility. That is not to mention the speed with which Linux itself is updated. Security holes and bugs are quickly tracked and fixed, frequently in a matter of hours.
Nobody can put a price tag on that.
No, it is not commonplace yet to have your Linux vendor put you on hold for half an hour to charge you big bucks for online support like the other guys. And yes, there are situations in which online support is indispensable. But there are already options for online support for Linux, a business which has everything to grow considerably as Linux invades the corporate market. And in an emergency, putting a Linux server up and running can be done much faster than any of it's competitors. In fact, in many cases you can have a spare hard disk laying around for an eventuality.