At the risk of adding slightly to some possible confusion, Suse 9.1 is free, it's just that Suse does not offer the installation images (ISO files) for free downloading, except for the Personal Edition. Basically if you want to install Suse 9.1, your options are:
1. Download the Suse Personal Edition ISO image, and install from that. You can get that file from a place like LinuxISO
2. You can purchase the Suse boxed set from a retailer or Novell (which owns Suse) and install from that. The boxed set comes with some really excellent printed documentation, and arguably is worth the price just for those books.
3. You can download the Suse Professional Edition boot image, then perform an FTP installation. This article
does a good job of explaining the process. This is the route that I took, but in retrospect it took a very long time (due to the fact that you need to download approx 3.3G of data, which is going to take a while even on a fast connection) but the end result was great. Personally, I think Suse is a great distro.
As sether already explained, the source code for the distro needs to be made freely available, but it's perfectly acceptable for a person or an organization to charge their customers for support, technical help, additional software, etc.
Good luck with it either way -- J.W.