As far as teaching English in Beijing you can receive around 1000 to 2000 dollars in most places with opportunities of tutoring available on your off days. With the salary and tutoring that can all accumulate to nearly 3000 dollars. The only thing is no housing is offered and most places don't give you that mid- month pay and end of year pay.

As for Hong Kong people. I only know one guy from Hong Kong and his family is so well off that he really doesn't need a job. I believe he volunteered in Beijing. His monthly allowance was like 1000 dollars per month when he was growing up and his parents already own homes in both Hong Kong and Mainland China/beijing.