They need to make all bankers into monetary exchange vendors. Trading diamonds, rubies, shells, mems, tokens, gold, sigils, badges... whatever currency is available for your character's levels would be interchangeable to another type of currency at a predetermined, fluxuating, daily rate. Kinda like a free-flowing economy based on daily intake and output, a stock exchange if you will... oh wow... that's putting all kinds of ideas in my head... like graphed weekly rate history... playing the market & buying/selling at the right times for revenue. Break big or go bust... or just simply change whatever currency you want for a small market exchange fee.
Hmmm... that would be a whole new level of in-game auctioning... no items, just currency. Wow... meh, but that's probably thinking way outside the box, and I don't think this game has the development team to implement something like that. Pipe dreams my friends... pipe dreams...
I love it. Sounds like a great idea.
Stockpiles of the "desired" currencies (diamonds and rubies mainly, but mentos, shells, justice coins, and pTokens could be included) are added every day to grease the cogs, so to speak. For the sake of example, 500 diamonds per server per day (week?). Limit how much of each resource an account can purchase per day. Then let the free market take it from there.
Example: Player A comes in and buys 10 diamonds at 10k a piece. Prices are influenced by demand, so they immediately increase by 10%. Player B comes in and buys 10 diamonds at 11k a piece. Etc etc until prices get high. Then the next player comes in and sells their diamonds for 55k a piece and the price drops by 10%.
They could enhance the gold sink aspect by charging a gold fee per transaction.
The limit of currency put into the game per day would have to be there to prevent huge infusions of those currencies, which would really throw the game out of whack. The limit on transactions per account would make it so more people could participate, and it would amplify the price changes based on demand.
Sounds like a fun and interesting addition to the game. Too bad the devs will never take the time to permanently put in something that would benefit the community like that.