If you're making a visit to Pondicherry, going to Aurovile is a must! it's beautiful and very peaceful. also don't miss out on the French colony. you can check for real good deals on hotels on booking.com
check for hostels if you're going solo
Also, don't miss out on the ferry ride to paradise beach. If possible keep the trip upto 3 days... there's lots to explore there and Aurovile itself might take upto a day