Personally, I think some of us spend far too much time and efforts in worrying about what others are doing.
There are constantly angry threads about ebay, discount stores and working untrained technicians.
No matter how much we talk about it, these people and places won't go away. So instead, why not spend your precious time on trying to improve your skills to a high standard so these people/places are not even consider a threat to you..?
I don't do minx, but if I did, then i will practise hard to make sure I turn out an excellent set of minx nails with no flaws. That way, even if my client manages to get hold of a set of minx on ebay, she will never be able to put it on as well as I do. And if by chance she does, then good for her and I will just move on to my next client.