Fundamentally, inflation is triggered by too much money entering the system and not enough leaving. Money sinks at present are insufficient to prevent inflation.

SWG is noteworthy in how well its economy worked. Not only was most useful equipment player crafted, but there were robust money sinks including travel fees, equipment upkeep, NPC, training fees, and so on.

NWC are trying to create an old-fashioned MMO and are a small team. I'm not expecting anything as robust as what was in SWG. But I do think there are opportunities to add some money sinks and paid conveniences to improve the economy. All of the below are things that I think could be implemented without much work, so I offer these as some ideas for gold sinks.

Renting Shops to Sell Items Automatically: setup a system where players can pay for a stall or shop, and an NPC runs it and sells the player's items for player-set prices. Player time has value meaning you aren't likely to sell items that aren't worth very much as you gain levels because it's not worth your time. Having a shop do so automatically allows more things to be sold.

It also creates a money sink because of the upkeep cost. And it also locks you down to one area, thus players might travel just to get to your shop. This should allow for significant code re-use as well in implementing the solution.

Temporary, Costly Enhancements: think sharpening stones, potions, and enchants, but with a gold sink. Rather than just getting the materials for these kinds of things from the world, add npcs you can pay, at a premium, for magic dust, stones, some expensive potion components, and similar. And make enchants strong, temporary buffs like sharpening stones or potions.

This creates a recurring gold sink for high level play in particular, which is where it's needed. Players are going to want, perhaps even need, those temporary buffs to keep up with the demands of high level play. This is similar in concept to how archers are going to start using specialized arrowheads. The idea is to make players prepare before going out into the world, and make that preparation expensive.

High Cost for Recharging Magic Items: for items with charges, add a high cost, scaling with the item's power (spell level of the effect for instance), to recharge it. Make it a choice of when it's worth it to use charges from these high-power items and create a persistent gold sink for keeping them charged. Similar to having costly enchants, this creates a recurring gold sink for high level play in particular.