I'm selling my backup housing from UK-GERMANY for the Canon 5D Mark II. I bought it used as well and only had it with me for one travel. It looks like new and is in great condition.
It comes with the 45° Viewfinder and Port for the 24-105mm or 100mm Makro.
Housing new: 2500 Euro
Viewfinder new: 950 Euro
Port new: 300 Euro
Total new: 3750 Euro
I would sell it for 50% of the new price: 1900 Euro / 2450 US-$ (excl. shipping)