Dynamic Field Prices V1.0

Makes Field prices more interesting. It might make sense to look out for good deals instead of always buying the closest land. Some NPCs are more greedy than others and their economic situation changes over time influencing the prices as well. An extra 10% is added when buying or selling a field. This will strongly limit field flipping. Prices change once per day. The difference to the base price in percent is shown when buying land.