Hi,

If I had $2,500 for buying Heuers and my most desirable model of the Heuer line was the Autavia GMT, I would prefer to spend $2,300 on this one:

than $799 on this one:

The first is mint. The second has faded bezel and... less than perfect dial.

Some people go for the deal. Some others go for the watch.
The later would choose the the mint Autavia because the difference in condition is invaluable to them.
The scarcity of some parts make imposible the improvement of a watch. I mean I don't know if anyone is able to bring the $799 Autavia to the condition of the $2,300 Autavia no matter how much money one is willing to spend. It this sense the $2,300 Autavia is invaluable.

This is my view and I believe that one should take it into account when trying to explain why some models fetch unrealistic prices. I'm the first to admit ebay is full of contradictions and strange prices, but sometimes there is an explanation beside ignorance of the buyer.