Hello,
I know this is a long shot, but maybe someone Dutch will know what would be the best course of action (if any) and whether it really is weird or whether it's just a cultural difference and it may be normal under some circumstances.

I've been looking into buying Sony-E PZ 10-20 mm f/4 G lens and I stumbled upon this ebay listing that has suspiciously low price (300 € while common price for used one is around 500 €) for a new, open box lens: https://www.ebay.com/itm/405687337337

Apart from the price what strikes me as weird is that the seller has already sold four of these lenses: https://www.ebay.com/fdbk/feedback_profile/reuv_0?user_context=BUYER - you usually don't buy five same lenses

What I noticed is that all lenses had torn packaging. So I though maybe they were supposed to be sold in a brick-and-mortar store but some accident happened and they can't sell them so they try to get at least some money off them. But then why wouldn't they list all of them at once? So I decided to ask the seller about this and also whether he could provide a serial number (I was thinking I could contact Sony support asking about the lens). The seller didn't provide the serial number (that seems suspicious) and explained the torn packaging by his son opening it roughly, but otherwise that it is new. That doesn't sound like a realistic explanation to me given that they sold at least four of these lenses like that.

What are your thoughts about that?

Lukas

Hello Lucas,
With ebay and neighter with Sony lenses I have no experience but in the Netherlands we have anexpression 'If it is to beautifull to be true mostly it is like that.

I'm sure this is not a scam in a way that the buyer would not receive the lens - AFAIK ebay pretty much always sides with the buyer in case of any problems. In fact if you are not established seller on ebay, they won't give you any money until the buyer confirms they received the item and everything was as described. If the buyer says the item did not match the description, ebay won't give the seller any money and the seller has to pay for return (even if they listed the item as no returns).

If it was stolen or otherwise sketchy (and not just an unusual coincidence of someone actually buying a ton of same lenses), then I thought posting about it might help the original owner to get their lenses back. There might be some local pages listing stolen equipment or something like that someone can check.

That's correct ;-)
https://www.fotoapparatuur.nl/Stolen

I have all my gear registrated by Lenstag ( https://www.lenstag.com/) If my gear is stolen I can add it there and I can check if something I want to buy is registered as stolen. I don't know if it needs a serial number to check that (haven't tried)
The story your seller uses for explaining the torn package is really sketchy when he has sold more of the same in same condition, I wouldn't trust that. Sounds to me like someone robbed a store and tries to sell the stolen goods ... maybe report to ebay that somethings not right there ...

Thank you, exactly my thoughts. Reporting to ebay sounds like a good option - I can imagine they can ask the seller to provide an invoice or some other proof of ownership.