There are some small tidbits on the Hong Kong cram school market in this 1 June 2009 NYT piece “In Hong Kong, Cram School Teachers’ Image Rivals Pop Stars“:
(…) Government statistics from 2006, the latest year available, showed 34 percent of the primary and secondary students in the city, or about 300,000, went to cram schools. With students typically paying around 1,000 Hong Kong dollars, or $128, per person per month in fees, the tutoring industry is generating at least 3.6 billion dollars a year, and that is probably a low estimate. A 2005 survey by the University of Hong Kong found that 70 percent of high school students and about 50 percent of primary school students had hired tutors.
To meet the demand in this city, which has more than 800,000 primary and secondary students, four dominating cram school chains have sprouted up, along with 800 smaller ones and many more private tutors. With more and more competitors entering the industry, which has a low entrance barrier, after-school teachers needed to find ways to attract students, and the so-called tutor kings and queens were born.
“Schools are like modeling agencies and tutors like stage actors,” said Richard Eng, an English tutor king who is co-founder of Beacon College, a cram school that is registered with the Hong Kong Education Department. “It’s human nature that we like to look at something beautiful.”
For Mr. Eng, that means wearing designer clothes and putting on foundation and lipstick for the camera; all classes are broadcast live via closed-circuit television.
(…) Mr. Eng declined to disclose his monthly salary, but Chinese media have reported that the top 20 tutors in the city have each made more than 10 million dollars a month. Mr. Eng, who owns a row of houses in a high-end residential area, has a yellow Lamborghini and a silver Mercedes-Benz.
There are no details on methods, class size, etc. I presume the model is similar to South Korea. Keep in mind that a if you can attract a class size of 50,000 then the same infrastructure can deliver the product to 1,000,000 students (the marginal cost of additional students is very low).