Buying undeveloped land
...is nothing like buying a developed property. With undeveloped land there are legal hoops to jump through. Is it in a flood plain. Most jurisdictions require soil perc tests. Some land can't even have on site sewage disposal. And there never is any guarantee of good potable water. Drilling through rock with some total depth and we're talking some real money.
Learn about the foregoing factors and you may learn why the price of the property came down.