There is the option to open a private stall and trade via it. Reaching level 30 and the second chapter of the Artisan Manual in the Chapter of the Nascent (V key) is required to unlock that feature. You will then be able to set up your own small stall, just select the Stall from the menu at the bottom right. You will need 100 Gyth Notes to do that.
Afterward, your character will change into a cute NPC: with that appearance, you will be unable to use skills or move, but you will be able to access your stall. You can keep chatting and using other interfaces. You can give your stall a unique name and later even change the standard merchant NPC model for some other.
The fee for selling the items at your stall is just 3%, which is even less that the Auction fee. Unlike at the auction, the storage charge is not incurred. Besides, you can open your stall wherever you choose. For example, it makes sense to sell equipment upgrade stones right beside the smithy. This will help you sell your items quicker.
You don't have to specify a timeframe in which the item must be sold, as the stall will stay open for as long as your character stays there. Also, there are no bids here: items have to be bought at once. Items can only be sold and purchased at stalls for Gythil. You can choose both the items you wish to sell and the items you want to purchase yourself. The other players can sell you those items if they are satisfied with the price you offered. The stall also allows you to chat with your would-be buyer. This can be useful if you have to be away from your keyboard for a while: their messages will not become lost in the general chat and will await your return.