The microeconomics of operating systems (OS's) are quite unusual. What is the cost to produce an OS? Are we talking about the OS as a whole? Or one copy? The cost to produce the device hardware on which the OS will run is easier to estimate — it depends on the costs of raw materials, semiconductor technology, assembly labor, shipping, etc. — but software production is more complicated. Certainly, the cost of obtaining a copy of an existing open-source OS is quite low: all you need are an internet connection and a 2 GB flashdrive.
Even if OS production costs can be estimated, it's not clear how simple economic concepts like supply and demand could be applied. What is clear — and you could establish this with a survey — is that Linux holds substantial value to those who use and support it. Yet, at the societal level, the perceived value of Linux (and of FOSS more broadly) is distributed across individuals in an odd way. Think of web servers that, with Linux, run Apache and collectively handle half of the internet's traffic. From Linux server sys admin, to server owner, to users of the served website, the perceived role and value of the server software vary greatly.
Personally, I believe that the spirit of the open source movement is an overwhelmingly positive one. I hope and believe that FOSS awareness and adoption will continue to rise. That's not to say that there isn't a role for proprietary software in certain niches — Mathematica being a prime example. As society becomes increasingly comfortable with technology, I look forward to a collective realization that stable, secure, open operating systems are incredibly worthwhile.