Here are some of the ways of acquiring openSUSE.

You can go to the openSUSE website and download a DVD ISO or a Live CD ISO free of charge. The ISO will then need to be burnt onto a CD or DVD as an image.
http://software.opensuse.org/

The DVD provides the most smooth and complete experience.

The benefits of the Live CD is that it's a smaller download, you can try it live (i.e. running only from the CD and RAM) on your hardware before installing anything and you can even use it to create a Live USB stick (See next chapter).

There are many webshops that offer to sell unofficial media (CD, DVD, USB-stick) with openSUSE very cheap. This is of course absolutely legal, as we're dealing with free software.

This saves you the trouble of downloading and burning the media yourself, and the subsequent risk of errors. See for example:
Linuxpusher.com
OSDisc.com
Linux-online-shopping.de
Linuxiso.co.uk

The Linuxpusher.com unofficial openSUSE DVD

The official box set contains a dual layer DVD with 32-bit and 64-bit openSUSE, an additional CD with non-free software and a printed start-up guide as well as 90 days installation support. The box set is convenient, looks good on your shelf, and the printed start-up guide is good to have. See:
http://en.opensuse.org/Buy_openSUSE

By buying the box set you support the openSUSE project

You can find the source code for all the free packages in openSUSE here, in the form of source RPM files:
http://download.opensuse.org/pub/opensuse/source/distribution/11.3/repo/oss/suse/src/