Every applicant - in your case 2 people need to pay Rs. 4,600 for the visa application fee plus Rs. 281 for the VFS service charge at the HDFC counters. Whoever goes to pay needs to take copy of the first page of the applicants' passports (2 in your case).
When they go for interview, they need to carry Rs. 2,300 per person Demand Draft for the visa issuance fee, which will need to be paid in the consulate if and as soon as visa is approved. If visa is not approved, this DD needs to be cancelled and money (less the bank charges) taken back. This DD needs to be in the name of American Consulate General, Chennai, drawn on any nationalized or private bank. (Cooperative banks not accepted).
Hope this helps.