The duchy, being an RP-focussed guild with a large scope, also seeks to build a stable economy between our members, allowing them to profit from selling items/materials to the duchy directly, as well as purchasing those same items at a cost that is set to make working within the duchy more advantageous than buying from the trader. While this means gatherers will not necessarily get top dollar for their gathering, by selling at ridiculously high prices, they can still make a fair trade of goods/services, and contribute to the guild bank, rather than being expected to just donate to the guild coffers (though we won't say no to a donation, of course).
Goods sold to the duchy will be stored in the guild bank/treasure trove, and sold to members at a discounted price, but if large quantities of a material are gathered and are not being sold to members of the duchy, those goods will be "exported" via the trading post, and the funds will go into the duchy's coffers for use as payment to guild members, guild events, rewards for any contests or competitions that might be held, as well as purchase of siege weapons for WvWvW PvP (thus helping to limit the personal costs to those who carry our banner).