Hi Nik/Abhijeet,
Most of the placement companies in india does not take any money from the candidate instead they take the money from the company which has selected you.
The money that they will charge to the companies is depends on your CTC offered by the company. It usally very from 8% to 12% based on certain factors like rare skils, number of experience etc.
However there are certain companies which does not entertains these placement firms.
my two cent.
Regards
Naveen