how much commission will h1-b consultancies take for MS graduate?

[desidakkan]

I graduated with MS Computer Science from New York. I want to join a consultancy that sponsors H1-B visa. How much %age will they take from me? Is there a database of ratings or commission values?

I cannot find a database of consultants. Anyone has info? Thanks in advance.

[immihelp]

Database is available at http://www.immihelp.com/h1b-sponsori...nies-database/

However, it does not provide any financial data about how much money they make.