have a plot in samaypur badli 170 sqyd

I have a plot in samaypur badli 170 sqyd. My father bought it back in 1991 and now i am having all the trouble to sell this one.
When i go to any property dealer, they say this place is unauthorized and they dont give any thing above 12-15k
now just 200 mtrs either side is Rohini and rates are sky touching as you all know.

Any suggestions on how can i check what is the current status of the property legal unlegal/Unauthorized??
Any help would be really appreciated.