Easy thing to balance evil spell lists are following ways (that I use):
1. For every 10 powerpoints they use to that spell list, they get one corruption point. When there are 100 points, their character will be taken over by some evil force (depends from the setting)
2. Evil spells are illegal to use, learn and it is illegal to carry spellbook that contains those spells (if that person don't have permission to do it). If there are "colors" of magic in the world, then evil spells are more easily recognized by certain persons (not all though).
3. Evil spell lists are very hard to get (very rare).