Well it depends, currently there are really no brick and mortar stores, banks, or currency exchanges buying back so at the present time you can really only sell either on ebay, on Dinar forums or back to a dealer.
Some dealers will only buy from people who bought from them and pretty much all dealer buy at prices most likely well below what you bought at. If the Iraqi Dinar were to become a tradeable currency it would be dealt with by many more banks and currency exchanges.
If you need to get rid of the Dinar now you can always sell either on ebay or to a dealer.