I think you all know this, but I'll leave it here just in case. You can get infinite gold by fishing, you can fish and sell to the fish dude 3x a day. And when you are fishing there is no limit on how many tries you make so you can keep trying till you get a fish that sells well. For example in the beggining you can get a fish that sells for more or less 500 gold, do this 3 times and you get 1500 gold, then use 100 to sleep on the inn, then just repeat the process again. The interesting this is that the more fish you sell, more fish medals you get, and with those you can get better fishing gear to get even more money.
So the whole moneylender is kinda pointless, you can just grind fishing to buy everything you want.
Hope it helps!! Great game btw!!