I'm currently working on a project that uses work covered by the CC-BY-SA license:
In the license, it states that I can:
Adapt — remix, transform, and build upon the material for any purpose, even commercially.
ShareAlike — If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.
My project itself can definitely be considered a derivative of the licensed work, or at least builds on it in a way that I'm happy to accept it needs to be shared under the same license as above.
What I'm unsure of is:
If I sell my derivative work, am I also required to share it for free? Or can I sell it how I like?
I'm aware that no matter how I distribute my work; I would have no right to prevent anybody else redistributing it for free (or even make money from it themselves). But it's quite a different situation if I'm also required to provide it for free.