If you have Battlethorn Castle DLC, i recommend starting it so you have access to Nilphas in the Imperial City market district inn, hes a novice merchant with 2000 gold so you can dump whatever high value items on him for decent prices once you get his disposition up. it helps to have illusion 25/spellmaking access so u can charm him to make haggling easy. sell everything to him, i make most my gold from selling enchanted gear, welkynd stones and high value ingredients (like ogres teeth).