Inflation - Evony designers must fix!
The game itself has a serious problem with an ever-increasing money supply that will continue to create inflation. Prices, in the long-run will continue to rise, as they have with all older servers (I play on Server 2).
The problem is that money is never taken out of circulation and it is constantly being put in circulation by NPC cities. Resources, on the other hand, are consumed (destroyed) through the purchase of troops, walls, and upgrades and battles (troops die). You can trade gold for other resources, but that gold is never destroyed, just used to buy other resources by someone else.
The Evony designers have to fix this problem. The way to fix the problem is to have a central bank (like the US Federal Reserve) sell resources on the market for market rates, but then "destroy" the money. This is essentially what the Fed does when it raises its various interest rates in the U.S. (Apologies to macro-economists everywhere).
One more point, I realize Gold is destroyed when research is purchased. But after a player purchases all research, he ceases to destroy any gold in the game. Thus, in more advanced populations the flow of gold into the game is unchecked, because most players have finished research.
-Cinnedigh