At first, we were thinking about some random store across the map to be used for upgrades, but because of time, we choose this anvil instead. One downside with the anvil is that it remains on the map and that place can't be used again for other buildings. you buy an upgrade and have less space on the map. About the flexibility you are right, we will try to come up with something, maybe by adding some more buildings or adjusting the game a little bit. Thanks for playing and for the feedback!