I think the charge is reasonable. I don't want to charge 300, but I only charge 300 if the students are willing to pay 300. I am confident that the effect of my class is definitely more than twice that of those teachers who charge 150. Of course, my teacher's charge of 500 is more than five times that of those 100 teachers.
Let me put it this way:
Most cheap classes will not only make your study progress, but also ruin your voice. Most expensive courses will make you progress. Although it is not necessarily proportional to the price, it is still reasonable.
So whether the charge is expensive or cheap depends on the cost performance. If you break your voice, although the charge is cheap, it will make you unable to sing, which is worse than not learning. I think it is really super expensive. What did you say?/Sorry?