Osiris, thanks for the compliments on my work. My ability to do this came from what I learned on the V/A subscription site. Kel-Crete is not needed in a vert mix, I was using it for a couple batches, then learned it didn't help at all! And many artisans around the world carve beautifully without specialty additives. Get a subscription, and watch the videos a couple times. It shows you how to make your own tools, and even mix ideas. You can do this, and it sounds like you won't have to deal with any competition, either! Best wishes.

Do NOT wait 2-1/2 years (or even 6 months) to do this! I had many unavoidable circumstances which delayed me so long. Join the subscription site and watch those videos, and talk to Nathan about sourcing your own mix. One video series shows Nathan doing a vertical job in Mexico using locally available materials. He will help you figure out your particular details. I don't make my own because it's easier for me here to just buy a mix. 

Another source of training is Bryan Gauthier, and for sheer volume of information, his is next to none. He gives many recipes for every sort of mix imaginable, and training for every decorative concrete work under the sun. If you can afford BOTH Bryan's AND the Vert/Art subscription, do it. If $$ is tight, like for most of us, choose very wisely...

In the end, my personal opinion is that there is no carving style like that pioneered by Nathan, and so the best way to learn that style is directly from him. When you see it all for yourself, you will probably feel bad for him for charging so little for what he gives.