Where I live, if you calculate how much a girl makes per hour from their job teaching Chinese or English, they make approx. 10 -  20 RMB per hour.

Paying them 50 RMB an hour is more than fair, and you will have no problem finding a teacher who will do that. plus buy them a coffee or milk tea.

Im Lucky I get 2 for the price of one

My wife teaches me and my 19yr old son helps with a lot of sentence structure

I still have a lot to learn however every year we go back I understand heaps more.

PS:

Welcome to the Nut House

0 girlfriend. .......................................

actually dinner and a movie 2-3 times a month.

I second Junglelife, 50 RMB and buying their drink if you meet at a coffee shop seems the most fair and respectful of their time.  I actually am offered by many Chinese girls who want to help for free or exchange languages, but to show I want to seriously learn, and not just pickup a hot date for "studying", I always pay something.  Many college students are interested in teaching Chinese, and while most will volunteer just to have a chance to make a foreign friend, I know how poor most of them are and will pay them like they are a professional.

I think a fair amount would probably be 10 rmb per hour. If I' m feeling generous i will throw in an extra 5 rmb and give them a smile and a cupcake! Oh sorry, I meant apple! 

hehe, you spelled "torture" wrong

You could get a college student for cheap. Less than 50.

In America, I paid over 230 RMB an hour, but didn't study long enough and my teacher actually punched me for not studying. I just liked to practice pronunciation, and got almost all of it down.

Now I'm married, and my wife beats me when I don't know enough Chinese. So, I guess the real cost is domestic abuse...

Pay...?

I pay 80RMB for a 90 minute class. The girl is fluent in 5 languages including English so she will understand any question I have.

You're a bunch of cheap buggers! 

Several years ago when I'm in the university my classmates charge their foreign students 15-20 RMB per hour. The reality is most of the Chinese students just want to have some foreign friends, and get some information that are fresh to them. But making friends and learning language are totally different issue....for me, if I hope to have a foreign friend I would find other methods to begin the friendship, such as public activity or exhibition etc., if I really want to change language, I will firstly make sure my Chinese is standard enough to teach somebody. A native speaker is not equal to a good teacher, I know how to say Chinese, but it's really difficult to explain some grammar which are ignored because too familiar to us to think their meaning.  Find a tutor come from Beijing, for even I sometimes couldn't understand some southern provinces ' accent....

I was offering 70yuan/h and couldn't find anyone willing to teach me Chinese... I think I was in the wrong side of China... uh.

I'm not sure. I always use the bargaining strategy so it varies everytime!!