In my case, I might teach a very gifted student for free, or a very sincere one, but I would also expect more of them since they are getting it for nothing. He has a medical practice and to take time away from healing his patients for a poor student is something he deems wasteful. Another post advocated learning basics from video as opposed to learning from a teacher. This logic was based upon a bad experience with ONE teacher. ONE teacher is hardly a good sample size for such a conclusion.
Teachers are necessary and good ones are hard to find.
THAT is desire and dedication worthy of consideration. Tai Chi does not have to be an acute learning situation. Why not teach a few select moves for the first several classes for the purpose of conditioning. It gives you the opportunity to spend alot of time on quality stuff and not memorization. Gung Bu stepping across the floor to understand the shifiting of weight.