1.Go to the Dark Mage shop in Tarant and enter it (only do-able at night).
2.Rest until morning.
3.Go inside and position yourself right beside the Dark Mage's shop chest.
4.Rest until evening, then rest +2 hours.
5.Either cast the spell Disintigrate on the Baleful Hound, or use a scroll of 
  Disintigrate. Melee combat will draw the shop owners attention and ruin it. 
6.Once the hound is dead, make sure you are still beside the Dark Mage's chest, 
  against the wall. Unlock Cantrip or Pick Lock the chest. 
7.To get the Light Mage's chest open, use Unlock Cantrip from the same spot while
  he's asleep. The Light Mage usually won't notice, since you're too far away. 
8.When needed, restock the chests by going outside the shop and advancing time 1
  day. It might be a good idea to Unlock the doors leading in to the back area. 
  Each day will yield around 5000 gold, and a number of various scrolls which can
  allow you access to high powered spells VERY early, as well as magikal items.