I would say it is very difficult to value a acre of land. So many things have to be considered. Is it an acre on its own or part of a larger pacella,? does it have a building or not?, does it have access,? does it have water,? does it have a power supply? Is it near a village?, a main road,? a beach,? nearby neighbours? Is it strategic to some other land? Does the owner want to sell it? How much does the buyer want to buy it.? Its real value is what the buyer will pay and the seller will sell at. :'(