Well, pricing is going to be fake and made up anyway.
Here's what'll happen:
1) Some enterprising grey market dealers will post up some listings on Chrono24 to put out some feelers at very high prices (maybe it'll start at $900k).
2) The aforementioned auction will happen, the bidders will think the market price is around where the handful of greys in step #1 above set the floor at. The auction will complete at or above that valuation.
3) Everyone will say "Well, the auction matched up a buyer to a seller, so clearly that's how free/open/efficient markets work, and thus this is the price! Whatever someone is willing to pay is the price!"
4) People from step #3 will die on their sword swearing that this is how it works, failing to realize that this isn't an efficient liquid market, so it's irrelevant.
5) Everyone else, including the very reputable grey dealers who don't participate in step #1 will latch onto that pricing.
And voi la! This is how you artificially inflate valuations and continue to perpetuate the horrible state we're in (i.e., "watches are investments").