Hi
I am planning to move from Mumbai to Colombo with family. So far, I have found out that rent is quite variable depending on area and configuration. Typically, a 2 BR will cost you around LKR 80k in Rajagiriya, around 40-60k in Wattala.
If you are still in Mumbai, we can catch up over phone. My no. is 9920333122, email is jnirban@gmail.com
regards, Jai