I also think AGF requires a Unity license to sell what you make, and those do not come cheap I fear. One of the goals we had with Reloaded was to allow you to sell what you make without some insanely expensive yearly license or horrid revenue splitting agreement.
The current terrain editing features are what I would call 'a first stab' at some basic controls for raising and lowering your landscape, and populating it roughly with textures and vegetation. I certain expect to see a fine-grain approach sometime in 2014 when we can take greater control of terrain sculpting and more accurate texture and vegetation placement. Once the core elements are done, and Terrain Editing PLUS gets voted in by the community, then your wish will be granted! Terrain editing is one of the things I will need to do personally (I suspect) so it should be good
Hogging the awesome since 1999