AnotherGame is a mod for ToE 3.1.

The market itself is primarily a tool for selling surplus resources. It is not economically beneficial at all, and trade is used only in emergencies or for resources that are essentially useless. It turns out that you have the same approach to developing mines – only in emergencies (I can't imagine when there would be a surplus of gold). But again, if you compare it to a warehouse, the upgrade price should be adjusted accordingly.

So, if we were to base it entirely on the market, the price would be around 35,000. I have a fifth of that. But the payback period should not be less than a week, and the prices for all upgrades should be the same. For gold, that's 7,001 gold. But the number isn't very appealing, so I increased it to 7,500. In the end, the market only adjusted the cost of mines by 2,500, not 30,000 :) +
Maybe we can analyze it with a specific example?
Necropolis? Elf? Would it be profitable to upgrade a lumber mill for an Elf?
The problem is not only in the resourcefulness of the map, but also in the choice of difficulty ;)
Maybe then, let's choose Veteran difficulty and medium resourcefulness. (On maps from IRMG, the resourcefulness will be high, but the hero difficulty will be high)