Stone being a very durable material is well sought after for constructing buildings, especially for those expected to last for a long time. However, stone itself is not easily handleable for construction out of the ground, so shaping it into regular blocks allows for greater and more easily utilization.
Per building level, at the goods' default market prices: the base cost is what the goods it uses cost, the base revenue what its output sells for, and the base profit the difference. Prices in each market move from there.
