[Cyclop]

People get cheated out of payments all the time ... but think of it another way, could the contents be worth more than the payment for the retrieval of the item? Most would think so unless the item has personal value.

I had dispel magic as the only way to open the item. Knock in my mind would open a arcane locked door and I feel could be applied to the lock of a small chest. This could be my Last decision as a DM to allow Knock to open the chest ...