Well I have been trained with various coaches in China. The price is mainly based on 1 City 2 Coach level.
It's common knowledge that in bigger cities e.g. Beijing Shanghai, the price is higner.
For 1-1 coach sessions, Coaches in Beijing and Shanghai are normally charge 200-300RMB per hour (30-45 USD). For such price you will find some ex-provincial team player coaches. Which is quite sufficient for amateur level players to pratice some normal FH, BH technique and drills.
For some lower level, I once see a coach in Shanghai that only cost 130 RMB per hour. That is 20USD. The cheapest I can find is big cities in China. But he is more a "training partner" than a coach. He is a Chinese old lad with a good penholder block. What he basically do is just to feed you balls to practice. Can't even block my forehand spin well.
If you are higher level player, e.g. some city team level teens in some smaller cities. Coming to seek some higher level coaching. You can find some ex-national (team 2 or backup team of course) coaches. But ex-national doesn't mean they are better at teaching amateur player. I once follow one of such coach in Beijing for two month (3*2hour session per week). He used to be in the national team, once a training partner of Zhang Jike. He is very good at tactical theories from his experiences, and taught me a lot about these things. And he has very good skills to train with some higher quality players e.g. city team or provincial team member. But he is not suitable for me, what I need is more of basic skill and drill training at that time. I don't need that many experiences, I need skills to carry out those experiences. He charges around 50 USD per hour now.
Also I know a coach in Shanghai recently, who is ex-national backup team, ex-Fujian Provincial team player and ex-Fujian Provincial coach for two years. He just moved to Shanghai to start new coaching business. Start with 37USD per hour 1-1 session. I want to train a few weeks with him when I travel back to Shanghai for business. But he didn't take me. Saying that he want to take some long term pupils.
In smaller cities, it's much cheaper.
In my home town which is a 3-tier city. My coach charge only 15 USD per hour, City team player level, good at feeding and drills, which is sufficient for me. In some other cities, you can find some coach as low as 10-12 USD per hour.