Is it possible (and legal, and to be precise: EULA does not necessarily mean law) to buy Mac OS X (without Apple computer) for the purpose of virtualization on a PC?
This is possible, but with limited success. It's easiest with older Mac releases where there was still DVD media, but there are instructions out there to show how you can create images from your Mac if running something newer. You'll need Apple's magic string which is embedded into every Mac is a pseudo encrypted way (again, you can find the magic string by using utilities found on the Internet, shoot, somebody has probably posted it. btw, the string sort of suggest that what you are likely about to do is illegal). There are other things you have to do, again, there are many recipes on the Internet, just google. Maybe that's not a good answer, but the info is out there on many many sites.
So.. you can "do it", but the result is always a violation of Apple's terms (always). Simply put, Apple does not really "support" the world of virtualization. At least not yet.
There was a debate on whether this is legal or permitted by the OS X Eula here: