Yes, I'd exclude anything on the secondhand market, especially things you have to buy from overseas sellers where there's no possibility of support or returns. This is not like a normal new part where you can purchase it firsthand and expect it to perform as advertised or else get a refund. Furthermore, the (Intel) chipsets on motherboards sold to consumers don't normally support ECC either, so it seems you'd have to get something that's not designed to Intel specifications, probably on Aliexpress, so it's questionable if ECC would even work, and you can certainly forget about any warranty or returns.
Seriously, if you can't just buy it at Best Buy/NewEgg/Amazon (not from 3rd-party overseas sellers), then it's not applicable to this discussion at all.
https://www.ebay.com/itm/305342386279 (note: I don't know the seller)