I bought it for $10 ("$40 off") and that's still how its listed for me. I never tried the other free options but reviews online were consistent that X410 was good. I've been happy with it.
I've also been pretty happy with it, and substantive new features are added regularly. There's a couple little annoyances from the design assumption that the user's main interest is WSL, but for the most part, it's been much smoother than the other X11-for-Win32 variants.
Support was recently added for listening on a hyperv vsock, but again, it assumes that you're using Windows on the hardware and connecting to a virtualized Linux. The vsock-win32 driver for KVM is supposedly coming soon and then it will be fun to explore just reversing the tunnel and see what we can get done that way.