Martin Logan Descent subwoofer

I purchased a Descent subwoofer and it was damaged in shipping. The front and 1 side grill were both damaged. The front grill can no longer be used, it rattles when the sub is operational. Martin Logan no longer makes the front grill, and politely avoided answering this question when asked. The shipper wants to know the value of the sub. I would rate it a 4/10 on the Agon scale. Im asking for your opinions since this is where I would have to resell the sub. The item was insured, and the shipper has refused to pay until I can provide a fair market value of the sub. Your help would be greatly appreciated.