I'm surprised they even have a website. This thread: https://forums.servethehome.com/index.php?threads/10gb-sfp-rj45-100m.45817/ suggests a couple brands off aliexpress that will probably be available in Europe inexpensively.
That's a good pointU.2 drives are great, but very few of them support ASPM and idle power is usually around 5W per drive, so you're looking at probably 25W total more idle power consumption than four desktop M.2 drives which do support ASPM and idle under 1W.