I am currently interested with some network cards on ebay. Looking at the pictures it mentions that the network cards are made in china. Is that a red flag? I have seen in the past that some mellanox cards were made in israel.
As far as I know, Mellanox uses manufacturing lines in various locations around the glob. One way or another, we tightly monitor our assembly lines and quality results for each manufactured unit.
Shouldn't be a red-flag.
At the same opportunity, I would recommend you to purchase cards from one of the Mellanox ' approved vendors or resellers. That way you can guarantee you buy a brand-new HW that comes with a warranty.