Guild Wars 2

Is there a way to adjust the sale price of an item you posted at the TP without taking it down and reposting it? If not, there should be.

No there’s not. You should be used to things not being in the game that should be.

Honestly this ability is not a normal AH/TP feature if at all present in any other MMO with an AH/TP. It is normal to expect to cancel the listing and relist the item paying the listing fee again. This is why it is important to think over what you will sell the item for and the possible amount of time it will take to complete the sale unless you are going to sell to the highest buy offer. A consequence free change the price of your listing would only encourage increased undercutting which has so many people in an uproar over as it is now. As long as you aren’t over charging the listing will sell sooner or later as long as there is demand.