This is in a UK jewellers in their pre owned section. They're an authorised Patek dealership so they'll know their stuff.
Can't work out if the price is £6,000 or £60,000 as £6k for what I assume is an automatic nautilus with day date and moon phase seems rediculously cheap, even at 2nd hand.
If it's a very good deal then may be worth a look, guessing may have some background to the Low price though : missing papers, box etc
No they don't. In supermarkets you get the item for free if priced incorrectly.
https://www.choice.com.au/shopping/consumer-rights-and-advice/your-rights/misleading-pricing