eBay used auto parts - orders cancelled

1. If you're looking for OEM parts, be sure you're actually at a real site. Sites like [Manufacturer]PartsDeal.com try their best to look and act like they're the OEM, but are not.
2. eBay sellers and many websites, use an inventory system to say a part is available, but don't actually update until someone makes a purchase, then discover the part isn't actually in stock and cancel the order.
3. If you want to see if a junkyard has the part, use this very simple, but extremely widespread site to check the actual inventor of actual junkards. I've been doing so for years - https://www.car-part.com - you'll want to call the junkyard, the "live chat" is rarely answered and look for somewhere local and go to pick it up yourself. These yards make the most of their money from other businesses, not individuals, so it make take some effort to find one that'll ship to you if you can't find what you want locally.
   You'll need some knowledge to know what to look for, if you can't find something let me know and I may be able to point you in the right direction for the search.

There's a very common scam in Germany on the local eBay (Kleinanzeigen) where the seller offers shipping, you pay, maybe get some fictional or registered tracking number and then the seller vanishes.

Maybe something along those lines? If you were to be paying with an instant payment thing?

Calling and asking is definitely the way for used car bits!

I've sold on eBay, the seller does not get to see your payment info, your CC is safe. eBay also offers fairly strong buyer protection too in case of a scam or other transaction issue.

I haven't tried to buy OEM car parts off eBay, but my guess is something like the vendor bought a heap of parts cheap, dug up the part once the order came in and then identified it as garbage. If the listing used generic pictures rather than user uploaded pics, that would reinforce the idea. If it was twice with two separate vendors, it could just be a standard operation for reselling this type of item. The timing doesn't raise alarm bells for me either, I just had a guy message me a few minutes after placing an order offering to cancel because he wouldn't be back from family vacation for over a week.

The official parts stores charge a massive mark up, even on after market parts, I wouldn't let the price discrepancy concern you so much either. Depending on the part, you may be just as well off calling a junkyard. It could be your best bet on getting OEM over after market.

Edit: to add, re tracking number scams. For expensive stuff, I prefer it sent to a UPS/FedEx facility, in part to avoid a costly porch pirate, but also to request they record me opening the package while recording info like the receipt with the time, a clock's current time, box's tracking number, item serial code. Never had an issue, but such a recording should be fairly bulletproof evidence.

Somewhat OT, but there are some categories that are so scam-ridden nowadays that I no longer use ebay and its ilk, due to almost guaranteed fraud, and unfortunately car parts are one of them.

For non-Amazon vendors, I use https://www.rockauto.com/ frequently. Their website makes it easy to drill down to what you need.