A family member of mine in Germany is looking for a laptop in the 100-200€ price range. It would be okay to buy used and it shouldn’t be one of those modern Celeron laptops. It should still have a fairly slim design and a processor at least good enough to run Minecraft at low settings with ~30fps on Linux. Is this even a thing, and where would be the best place to start looking?
Look for local companies that buy used corporate laptops and refurbish them. Lots of barely used Lenovo, Dell etc. computers.