My honest opinion is that this is them thinking about their business (& not very well thought out either) not thinking about their customers business (ours).
If they had looked at the big picture then they would have seen the obvious floors in the idea, it may well initially work to bring in money for them but it's not going to work long term as those of us who sold on their kits would then need less solution from them as we would have lost our clients so they would be losing our cutom.
These untrained people who had bought kits off us may well need to buy solution more often than us though as they would have no idea how to set their guns & that in itself means they would (more than likely) end up asking us for help setting their guns etc... and all that hassle for just £20 - I don't think so.
If on the other hand they are asking you to train these new therapists & then retail them the kit - I would first of all be thinking I need some sort of qualification to be able to teach, then I would be wondering if £20 profit per kit sold is enough to make me want to teach them, I'd be thinking I want paying really well for my time & knowlege not just £20 profit on each kit I sold.