traders and banks
we have no singular “server wide per side” auction house. we use a system of traders that offer most goods, either npcs or actual human players. i went through a period where i actually played lots of different mmorpgs. i played on official servers and development ones.
the experience of playing ragnarok online was interesting. oftentimes major cities were literally crowded with independent players with the “trading” ability.
the method of granting lower prices from computer vendors to characters with a certain trading or vending skill is what allows human traders.
high level items are traded by named characters with their own methods and pricing strategies. the “system” itself also manages large amounts of vending machines and traders throughout the game world.
players with mining and other craftsman abilities are often traders of items related to their particular life paths (we have few set “class restrictions” on learning skills)
i avoid a lot of the major coding involved in an auction house, but still have to create algorithms for the pricing strategies of each vendor.
i expect the tweaking of this systems will be ongoing for a while. trade between various cultures and nations in the game world will carried out primarily through specific traders who control currency exchange rates