Você pode definitivamente vender os itens no final do episódio ou aventura, de acordo com o AL Player's Guide (pg 7). Qualquer outra coisa é com o seu DM. Note que estes são distintos do final de uma sessão.
At the end of an episode or adventure (and sometimes during an adventure), you can buy or sell mundane items. Any gems, jewelry, art objects, and trade goods you find during adventures are automatically converted to their full value in gold and divided up among the adventurers in your group. Arms, armor, and other equipment fetch half their cost if you sell them.