You can buy the windmill. It's a dexsoft-product, as well as the two villager,the blackknightress and rocks. The Windmill is included in the "Medieval Farm Pack".
Basically every 3d Object in the scene is non-exclusive. But we will add some exclusive 3d Objects in the future. Our 2d Artist is working on a mage tower. I attached some concepts. Once the concepts are ready, an Artist will create the mage tower in 3d.