It's not an easy task. I once built a website followed by a video tutorial on how it works and it took me quite a long time to accomplish.
Perhaps doing in-depth tutorials on creating different types of landscapes or skies would be a separate topic, but I think that the essence would be a deep explanation of GUI and a black hole of node network together with all of its functions, connections, what to use, when and what effects to expect.
I would also teach people on how to achieve something globally first (a layer of clouds, a landscape populated with trees, a waterscape with nice sunset, etc.) and then cover the topics on how to localize elements (create different layers of sand and position it, mixing trees, grass and flowers, pebbles etc.)
On pricing - it depends.
You could release different topics with low prices (~5 EUR) or in bundles (essentials, advanced, master, etc.). I think that both options would be accessible to different people. For example, I feel pretty confident in navigating TG2 GUI but I'd like to fall in a little deeper in TG2's "black hole" as mentioned above ;-)