Well, judging from your join date, you should recall that the prices for recipes used to be higher, and the CE costs for crafting lower. This may have contributed to somewhat slowed crown inflation (i don't actually know if it did), but changing the ratio can't stabilize the prices on its own. The real problem is that once players have all the gear they need, there is nothing left to spend crowns on, and they keep accumulating them. A viable crown sink would have to be something repeatable that end game players would be compelled to do. In this way it would drain crowns indefinitely, and provide more incentives for players to sell CE for crowns.

Mineral boosting was repeatable, for example, but costs were exorbitant and players weren't really compelled to participate in it so it didn't work. Winkers' post up there lists armor repairs, which are repeatable and players have to participate in them (which seems a bit mean, but effective i suppose), and aesthetic buyables like costumes and housing, which though limited are easily designed and provide huge incentives for players to spend.

And while we're flinging links around, my own personal idea for a crown sink: http://forums.spiralknights.com/en/node/11293

So there are a number of possible solutions (that keep the current player-controlled crown / ce market model intact). I like any idea that implements costumes, because, well, the TF2 model seems to be doing pretty well for Valve over thar, but I think OOO will probably try another variant on gate construction since that was their original vision for the game.