I would price it in the $5000 - $8000 range, depending on if it has subgrades or not and overall appearance. A poorly centered 6 would be at the lower range, while a rough edge would be more forgiving. The card in my sig has three subgrades at 8 or higher, with just the corners bringing it down. I would put it at the higher end of my range. If you are not interested, plmk the details as I might be interested.