Mitsu has consistently had the best prices, plus they have good service and are domainer friendly. Right now they have an INR 200 special on for .in and .co.in.
All who register more then 20 domains (.IN or third level of .In domains) during the March,09 by paying INR 200 (or say USD 3.99) per domain, it is an extra incentive which we gave to our customers.