Yes! Simply login to Your Account and choose the selling tab.
In order to change price select EDIT on the reservation that you want to change the price for, enter the new price and click CONFIRM. Your reservation is now updated with the new price.
In order to change the quantity, you must cancel your offer to sell and resubmit a new offer to sell with any changes. When you cancel the offer to sell the reservations are returned to the RESERVATIONS tab in MY ACCOUNT.