Idea 1. Distance fee for buyers. Let’s say you’re selling water at 0.01 but someone else is also selling at 0.01 and had listed their water after you. A distance fee will give your water a chance because it’ll be cheaper to buy from you if the buyers are closer to the territory you posted in.
Idea 2. A stock market type market for resources. All the waters being sold gets put in a pool and the price is averaged. A buyer buys water from the pool and you get a cut based on how much you’ve invested into the pool. This one is a bit more vague, but the spirit of the idea is to give everyone a chance to sell.
Gold Ingots: Maybe make precious metals a currency for lets say, upgrading town projects or some such. Thus actually making gold valuable again (bc of market competition, and gold vein-rich territories would have an edge, etc.)
I never took an economics class, but I just think these would make things a bit more interesting.