my suggestion is to keep leveling the necro, your going to have alot easier time farming with a necro than a SK. in your 30's you can start kiting mobs that drop nicely selling items and or a few gold.
actually, SI (shrouded Isle) can be pretty good cash, unfortunatly, that is when you start venturing inside the mansion, which is around ~25+ but its a great place to level iirc it has a nice large zone exp modifier.