I agree I'd want no part of these employee's revenge on the shop owner ,You very well know that what you've recieved is pretty much a theft and as other's have said it would be hard for you explain that you had no idea of the value that you recieved for only 250.00.I would definetly take it back and explain to him what has happened and you wanted no part of it ,I'm sure you'll find that he's very appreciative and will definetly respect you for returning these item's.All it take's is for him to notice and call the cop's ,just maybe the guy who sold it to you, will tell him about you. Then this will make you look like you were part of it,and then you'll have no recourse and will be in as much trouble as the guy that sold it to you.
Take it back before it goes too far.Do the right thing.

nubo