I find this money lying around randomly useless, because, why would you pick it up when the items in the chests are worth more? I finished this game only picking up money bags that were 'free', as in, I didn't have to fight to get to it. You'll get enough money to buy most of the potions from the shopkeeper anyways, and don't buy anything BUT potions from that guy anyways, because your main gear should be from chests.