I had a nice trip to mamallapuram and stayed in TTDC beach resort, mamallapuram, near chennai. Just sharing with you.
1. Booked ticked from TTDC (TAMILNADU TOURISM DEVELOPMENT CORPORATION), chennai
Its 1750 Rs for AC Deluxe
2. 9 am Took Bus from Coimbedu, chennai. Every 5 minutes bus is available. All the buses going to pondicherry will go to mamallapuram