Hey,

I'm trying to see if this is possible to have an item proposed only once from a building, and then once bought you can't buy it anymore. That would allow to propose rather powerful items, instead of having them set with a super high price (to keep balance), as this would prevent buying them until the end game.

Or for example you want to allow a Brewery to allow the buying of one barrel of ale (+1 permanent HP). Players would have to build another brewery in another town to buy a new one. I believe this would be a safe way to balance and prevent any exploit. The new building would still have a minor side effect, like +1 gildar anyway.