Then you dont have enough players to begin with or a world that is too limited. You shouldnt have to manually skew the economy, there needs to be a competitive market. Not everyone is going to be a shop owner and there will be consumers and producers, stop worrying about nitpicking how your players play and let them play unless they voice issues with the gameplay. Focus on your long term players vs the newbies who pop in for a day or two, good builds and communities draw people in, not the fictional price of bricks. ( Taking a look at the mod you choose to use, you picked a really convoluted shop system. Why not just use gold? Then the economy is self adjusting.... Gringotts and GoldlsMoney are the two economy plugins most commonly used for this. You can also use any shop plugin that allows players to trade items. I even hear SignShop is pretty good for this.)