Thats fine...,
But they don't have a mine yet, so that doesn't matter right now. They must look this over for a year whoever they is. Realistically your looking at a minimum of 3 years or more and alot of money to get started, you don't just go dig gold, or else everyone would be doing it.
And why would they sell such a valuable piece of property with so much gold for 250k? If its so easy why don't they mine it themselves? Because its timely and very costly IMO.