At a certain time (random so no-one will know when) Caravans (selling hq gear items etc). could visit nearby the 3 towns (or perhaps near one etc). The special currency used to purchase the hq items at the caravan event can only be gained from killing mobs in an instanced dugeon (in a certain size group ; maybe 6-12 etc ). The Caravan sells the items (based on the developers pricing instead of market warding). The item can be sold still in a bazaar but no where else. Finally the caravan will appear 2 times a month or once every 2 months etc. Giving gamers an ample amount of time to party and do instanced runs (and this infrequency of having a vendor selling rare items) would discourage gill-sellers.
Also every 4 to 6 months have a 2 week auction shop appear where people can sell their items. This too will limit gill sellers (aslo placing reasonable restrictions on how many items a person can sell in bulk during his /her time online or the ability to sell multiple pieces of the same gear.
Think of it in real ife terms(if you had a unique helmet you wanted to sell to a collector or a pawn store he would probably purchase it from you within a reasonable price, but if you brought in 10 unique helmets to a pawn or antique collector he probably wouldnt find it all that unique. So by restricting selling of multiple rare items it discourages gil-sellers from farming NM's for items to sell for gold.
There must be a way to govern how often a person can sell the same item or multiples of a gathered item(like bulk weapons of high value or sets of materials in unusually large volumes.The user interface should obviously restrict anyone from selling multiples of weapons (particularly rare items to discourage illegal gaming behavior. Perhaps a limit of the items sold based on its value not valuing over a certain cap total value to disccourage gillselling etc.
These are concepts ideas for a better more versatile game regarding the option of a limited Auction House , and Caravan concept (encouraging instanced runs). Please feel free to brainstorm upon my ideas or help me to get this noticed by the developers. I am not exactly a "forum-savvy" individual but I would like to offer some form of contribution to the enhancement of this amazing game. ~Hooptymobile