Market Dominance
When markets are implemented as these kinds of homogeneous services by some obscure unplayable race (goblins!) in an MMO it gives an unrealistic amount of data to participants, and opens the door for people with enough time on their hands to unnaturally dominate markets. So lets say I'm level 4 and I want to sell some Copper ore in World of Warcraft. If I open up the Auction House I see every other market participant in the entire server. If I want to participate and sell in this market I'm essentially restricted in what I can ask for my Copper based on the lowest price point and the demand. This is what I call "flat-line" pricing. The reason price "flat-lining" is bad is that its a consequence of resources not actually being scarce in an online game. When resources aren't truly scarce they have almost no value. Green recipes in ESO are actually under this type of pressure now because they drop so often.
Market Clearing and Artificial Scarcity
Another problem with the size of markets and the problem of flat-lining is that at the lowest price point on the market essentially never clears. Meaning that the demand isn't sufficient to consume the amount of goods on the market at the lowest possible price point. This is a product of artificial scarcity. The only way to clear this type of market is to implement "liquidation events" like the old Ahn'Qiraj gate opening event in World of Warcraft. Commodities of all types were needed for the server-wide effort, and price flat-lining was eliminated for a time. If a "global economy" exists in a game there need to be alternative ways of consuming resources to offset the artificial scarcity.
Prevent "Flat-Lining", Promote Perpetual Price Discovery
In Elder Scrolls Online (ESO) if I want to sell some low level commodities, the limitation on the number of market participants prevents the price point from flat-lining. While some equilibrium does exist over the spread of a players' allowed five guild membership, the fact that not every player is a member of the same five guilds and that those five guilds are in constant membership flux allows for price fluctuation. This quest of price-discovery over the span of multiple guilds is more realistic and satisfying. In reality economics is often heavily influenced by things that don't have an analog in video games, like geopolitics and the resulting effect on the economic systems of countries with scarce resources.
An individual in ESO would have to go to great effort to dominate and flat-line a market, creating alts and colluding with other players who were members of different guilds. The power of an individual participant in the global market is limited. Even if they were to go through all this trouble it would be difficult to measure the impact.
"Flat-Lining" vs Equilibrium.
Flat-lining should not be confused with the concept of market equilibrium, although the end result of both is price stability. Price flat-lining is the result of overwhelming supply brought about by artificial scarcity, and no mechanic in place to soak up that excess supply. While some demand does exist for goods that are flat-lined, it doesn't come anywhere near "enough." Equilibrium on the other hand would exist in the market where demand meets supply, obviously. Prices reach a stable level and fluctuate based on variables in the market (i.e., people farming less, drop rates, shifts in demand). With flat-lining, although prices are bottomed out, many of the goods on the market remain on the market and never clear (sell). Eventually these are re-listed (at a loss) or sold to a vendor (for no profit). It's a delicate balance for sure.vs. Guild Wars 2
The Bad Stuff
Obviously right now they have a few bugs to work out such as the mail delivery system, and the poor functionality of the guild store interface... but overall I think its the best MMO economic system I've participated in ever.
The problem with "Trading Guilds" (guilds formed for the sole purpose of being composed of market participants) is that they have guild leadership structures similar to that of traditional guilds focused on PvE and PvP progress. You can grant and revoke rights to players and lock down guild resources from players... such as access to the guild bank.
In theory the participation and promoting of your trading guild is supposed to give you the advantage of having a great position for the Guild Trader somewhere in the world where participants outside the guild can buy things. This grants you the ability to sell things to a wider audience and ultimately benefit you. However the jockeying for position of the Guild Trader between different Trading Guilds opens the door for corruption of the guild leadership.
Fund raising events are common in some of the best trading guilds that I'm currently a member of. There is no open accounting of where the money goes, and what the guild leadership uses it for. This leaves the initiate, or the average market participant who isn't included in the "inner circle" of a trading guild a little skeptical and cynical about where his donations are going. The only thing you can really hope for is that the gold spent for the purpose of a broader market is being used faithfully and truthfully by the guild leadership. Problem is outside the inner circle, the 450+ people who are essentially just randoms don't get this reassurance.
But if you're like me, with a healthy distrust of government and government-esque institutions like Trading Guilds... you would like better transparency. The guild bank does show when funds are withdrawn and when they are deposited etc... but if the guild leader is not disclosing how much it costs the guild weekly to maintain its Guild Trader location, and is using those "excess funds" to benefit the inner circle... this is nothing more than cronyism that hurts the community. It boils down to a structure that facilitates exploitation of the masses using the carrot-on-a-stick of ensuring your Guild Trader is in a good spot.
Here are the solutions that would solve this.
Eliminate the guild bank for Trading Guilds
There is no reason to have it if it is going to be locked down from the majority of the guild anyway, and if its opened up it allows trolls who would steal its contents the ability to damage a larger pool of people. The entire point of a Trading Guilds is not PvE or PvP but trading. PvP and PvE guilds of friends use guild banks to pool resources that can later be used for the progress of the guild. No such goal exists for Trading Guilds outside the inner circle.
Redistribute Excess Funds Weekly
Excess Funds that were raised throughout the week intended to go toward the bidding of Guild Trader position should be redistributed automatically after the guilds Guild Trader spot is awarded. Since the Guild Bank already tracks who deposits gold and the amount they deposit, it should be very easy to redistribute all excess gold to players (proportionally) who deposited gold and contributed during that week. Players who do not contribute would not receive excess funds.
Eliminate Ranks
There should be no need for any administrative activities in a Trading Guild that would require guild leaders and officers. The automatic machinations of a Trading Guild should be fully automated.
Differentiate between Trading Guilds and Other Guilds
Trading guilds have a very narrow purpose, and shouldn't function the same as traditional guilds. The advantage of having a trading guild has already been explained as broadening your potential customer base when you sell things on a market. Traditional guilds focused on PvE and PvP advancement should be limited to ~50 players (maybe 100?) and have features like the guild bank unlocked. The explicit difference between these two guilds as a new recruit is that you're granting your sanction to the guild leadership to do what needs to be done for progress. As a new recruit in a trading guild you've got very little opportunity to break into the inner circle (often composed of a group of friends).
