Omega Seamaster Planet Ocean Liquidmetal Limited Edition *takes a breath*, no question.
$6500 would be a tough ask but I saw a gen (Obviously as there are no reps of this model and if there were they would be way off) on ebay for this price from a reputable seller. I'm lucky I don't have that kind of money unless I sacrifice my BMW fund or I'd have bought it.
If I couldn't get that, probably just a regular Planet Ocean Automatic. I would prefer a Milgauss Black but I asked the AD in Adelaide and he quoted me $8500. Then again, if I'd be willing to go to the bay for the Liquidmetal I guess I could go to the bay for a Milgauss but I'd rather hit up a dealer if possible.