One of the forum members sold an ungraded 1988 5 oz gold Dragon recently for a little over $16,000. It was still in its double plastic wrapper, but it had unsightly red blemishes.
I purchased a 1988 5 oz gold Dragon, graded NGC PF69UC, within the past few months from a friend in the price range mentioned by Badon. It is an excellent coin, without any problems.
If I were asked to purchase your coin, based upon your description, I would be frightened to pay $12,000.
As Badon mentioned,"condition makes a huge difference in its value."
By the way, what does "schowing marks" mean? I have guessed it means something terrible, but I do not really know.
Mark Bonke