Are you saying you called the apple store so that you can sell them back your old Imac computer to buy a newer model? If not the apple store which store did you contact? Do you have the email they sent you with the tracking number?
Apple does have a renew program which they will buy back your old products but they only offer anywhere from 35.00 to 500.00 (2007 and above) to purchase it.
From what I can see for the specs of the IMac that you have they will not give you more than 160.00 if that much. The IMac with retina is considerably more than your 1100 plus what IMac will give you. That is from the research I have done.
Good afternoon, do you still need help with your Imac?