There's roughly about 830kg of gunpowder in front of him. Excluding the remaining goods, just buying the three of them cost him about 1500 gold coins. However, it will only take one-third cost if he could buy it from the system.
This is probably the first time he actually gets to see that the system is offering cheaper than outside the world. After all, according to its policy, the rarer the item is, the costlier it should be. Does that mean gunpowder isn't a rare item?
When Mark thought about it for a moment, it made sense to him. After all, the ingredients he used were all available in bulk in nature and being utilized for various purposes in this world. He knew that people would try to reverse engineer his weapons.