Now i realize there is less necessity for such a market in Guild Wars, since there are no ammo, ships, etc, i still think that if the designers were able to incorporate busniess, entrepreneurship, maybe even stock into Guild Wars, that it would make it even more attracting that it already is.
Picture this.
You and your buddies band togeather to make a guild. So far you can do that. Now picture that guild deciding, "Hey! I dont see enough runes for Rangers around, lets make some." They contact the rich players and say "we want to produce ranger runes, would you be interested in giving us financial backing in exhange for a cut of the profits? (or stock)". They get the money (or not) and BAM. Money + Producing capability (Perhaps guild halls could purchase workstations that require resources to create products) + supply and demand (which already exists in some form via the Traders) = Player Market

Submitted for your discression. further ideas or criticism welcome.
Drake [LoL]