There have been many gold sink suggestions, but we want a solution that can be implemented easily within the current system. Time is important, as inflation is going on every single day. The economy will be more difficult to balance the longer we wait. This thread is for those 'Quick Fix' suggestions.
So for these suggestions, think creatively, and within the current system. Guild Hall improvements, Cosmetic additions, etc are long term solutions, but will take much programing, artwork, and database memory considerations.
So let me start with these:
1. One shot signets for pve. Buy them, use them once and they're gone. Or give them a 500 sec recharge time, and they're gone when you zone. Example - Regenerate all health, Regenerate all mana, Resurrect all henchmen at 60% death penalty, etc. Have them cost like 1 plat. So many possibilities here that will not unbalance. For pvp, you can have one shot signets that have disadvantages. For example ranger usable only twice normal duration healing spring, but also cripples the caster at the same time, or takes away some hp, or disables all other skills, etc. Or a one shot signet that resets all skills but drains hp or mana. These signets can be bought for 1 plat, etc. For pvp, it is harder to balance, but still quite possible.
2. Quick Fix "Auction House" + Gold Sink. Pay 1 plat to sail to Bazaar or Flea Market Island. Make it an International zone. Once you get there, you can shop for all the items that are posted. Any item that you buy will be automatically customized for the buyer (can't resell). To post an item for sale, give the item to any merchant in any town, give price, and pay 500g. The item will be posted for 24 hours, if nobody buys it, it is returned to the seller. This is for selling weapons only.
3. Reduce gold coin drops, but only at the higher player levels. Or make them like experience points, you get no gold coin drop if you would have gotten 0 xp from the kill. Items drops remain unchanged.
So remember, Quick Fixes Only in this thread. The above ideas are probably not unique and probably have been suggested before. This is to say I'm not taking any credit for them, so don't flame me

Quick Fixes Only!