If they ever really want to get serious about a gold sink, they should get rid of LRC. Maybe make it so LRC means you can have the regs in your bank box instead of carrying them around. Gold just doesn't leave the system enough
Reagents would not be a good goldsink, they cost a few gold each. It would have to be some item that cost millions of gold to be a useful goldsink with the economy we have.
Maybe have runics, which are not much more than goldsinks themselves, cost a million gold per use? That would be a significant goldsink.
Have artifacts be repairable only by a NPC Crafter who charges a fee based on the total bonus's the item gives per point of durability repaired. Say 10,000 or 100,000 gold a point. This would be a much more effective goldsink.
Increase the cost of insurance based on how uber an item is. Items with bonus's and abilities that are under 80% of the maximum possible cost what insurance does now, items with bonus's and abilities that are above that 80% point charge 10x more gold at 81%, 100x more at 82%, etc. Items at maximum ability might sink a few hundred thousand gold each for insurance. A much better goldsink than reagents, and would have little effect on the average or new player.
Maybe give Stealing skills to the high end supermonsters so they can steal gold characters have picked up and bags of sending characters may be carrying. This would help lower the amount of gold added to the economy yet still leave the chance of getting the item drops. Another better goldsink.
Place a higher vendor fee on Player Vendors based on the price of items it's selling and the amount of gold it's trusted to carry would be a good gold sink. Anything priced over one million adds a 10% tax on the price to the vendor fee. True, many people will just jack up the price to cover the extra vendor cost and still cry out $$KA-CHING!!$$, though some may just lower the price to avoid the added tax. Those that don't lower the price will sink more gold out of the game which really needs to happen with the game economy in the shape it's in. We would, of course, hear the Palace treasurer screaming $$KaChing!!$$ all the way to the Lost Lands. <g>
Have different classes of Player Vendors that earn higher wages due to the value of the items they handle? A standard vendor gets paid less per day than those vendors entrusted to handle million gold items. Those that handle items that cost 10's ot 100's of millions get paid a much larger wage. Those players that deal with items of such high value can certainly afford the added costs. Given many of the prices, can you say goldsink!
The Dev's could do a subroutine for the game that would track the items each player owns and the vendor prices those items typically cost and collect a 'property tax' on those items, sinking more gold out of the game. A big goldsink here.
Add a 1/2% handling and security fee to bank deposits and withdrawls? This would add up to a good goldsink when a Tower, Keep, or Castle sells, considering what they sell for.
A token goldsink like ending LRC won't even be noticable to anyone other than a newbie, or casual player who it would hurt. A major goldsink aimed at those who already complain about the huge amount of gold they have and the hassle it is would ease their gold clutter problem and remove a lot of the excess gold from the game as an added bonus.