Thanks for playing! The cost of construction or upgrade is shown in the top-right but it might not be obvious enough. The targeting is based on traditional Tower Defense games so I didn’t go into detail on it. Well spotted on the screenshot, that’s from a development build that sends a continuous stream of the same creeps that I used to test the map, maybe I should change it if it’s misleading.
Thanks for the feedback and congratulations on beating the game! 🎉