Ok well fighting in the arena is a big part of the game (well it is for me anyway and one of the more fun components to boot) and in preparation for arenas you often have to buy potions and what not (well if you do not want to be slaughtered anyway) which can be a drain on your pocket so all im suggesting is that you are also rewarded some cash for arena battles just like you would in a monster fight (as often times i get so involved in arena that when i look again i have no cash and am forced to then hunt monsters and what not instead of being able to continue grafting the arena like i would want to)