To get infinite gold, go to Castle Dour in Solitude. By the door to where General Tulias is there are three archery targets with guards shooting at them. Wait for them to shoot a sizable amount of arrows at the targets and take them. The guards don't mind you taking them. Once you have as many arrows as you want go to a smith/general store and sell them. When the store runs out of money wait two days and then repeat the process. You may do this as many times as you wish.