Inflation should still be allowed to run its course to balance its value from other currencies. If a stone was implemented to buy ED for gold then ED's would not be exclusive through donation only, which would defeat the purpose. Maybe a market, available to everyone ( [market command for example ), set up where players can sell (In-game ED) to the highest bidder or buy from the lowest seller. (A similar market system for multiple items, goods, and currencies is in-place on UO Excelsior and still fluctuates based on inflation daily.)