I suggest having an NPC shop of vanity (costume only) items to drain the economy of its crowns. Either that or some other way of draining Cr. I don't think that there is enough Cr draining out there already that is taking Cr out of the economy. Things like the auction house keep most of the Cr in the economy. The inflation occurs because Cr are increasing and the supply drive the price of Ce up. This is a problem for the market since the amount of Cr you obtain from the Clockworks is the same on average.
Also, it would be nice to have a graph of exchange rates fluctuating over a period like that day and a few months back. That way, players can accurately analyze supply and demand instead of assuming that the four best prices represent the whole economy. Essentially, if you give us more information, we will be more likely to set a price closer to what it should be.