Nazarana on watan land

Sir/ Madam l have land which need to sold however its watan land and 50% Nazrana need to be paid of market value. I want to understand when they say market value dose it mean that we need to pay 50% of market price for which we buy or sale the property or 50% of the government value which they publish each year in a book by revenue dpt from were we calculate the stamp duty . Please help as buyer is saying that he will pay me 50% of market price as he will have to pay the Nazrana eg. If the market price is 10 lacs he will only pay me 5 lacs when the government value is 2 lacs for that land. PLEASE ADVICE Sandeep