The Cost Of UNIX

Can Anyone Tell Me The Cost Of UNIX As I'm Considering Finally Getting Rid Of This Rubbish Windows Based OS. I Would Also Like To Know Anyones Opinions On The Best Free Version,

Thanks.

From http://droflet.net/unix_dot_com_faq.html

Q: I have a spare Intel box to install Unix on, which version is the best?

A: There is no single "best" vendor. Intel machines can run Linux, *BSD, and Solaris. Linux is available from various vendors such as Redhat, Mandrake, Suse, Slackware, Debian, etc. Solaris costs approximately $75 for the source media, or you can download it for free from Sun's website. The download is approximately 800 megabytes. Other distributions range from $5 on up depending on the level of support you get with it. Many may also be downloaded for free from the Internet. If your goal is to simply learn Unix, any distribution will probably work. If you have a specific purpose in mind, please research the appropriate vendor websites to determine if their product will meet your needs.