An update to the above post if anyone is interested…
I received few replies from OPW. All of them say the same thing.Permission to photograph National Monuments in State Care for commercial purposes requires advance permission, and a fee for such photography may be imposed. This permission is not given retrospectively.
So, photographing landmark monuments or buildings for commercial use is not possible without permission.
Canon is a year old. Sigma is 2 years old. I do not no how much the current market price, these may vary depends where you buy from. It could be-350-430
Media man, The lens is in very good condition, as new. Used only few times. I have a 18-200 now. That is the reason for sale.