The 10 GBit/s NUCs you find on eBay are enterprise-grade stuff: 10 Gbit/s hasn't really been a consumer thing. A used Fujitsu, Intel or Mellanox dual 10 Gbit/s bought on eBay isn't a "stained shit" that's "not guaranteed to be reliable". It's enterprise grade hardware.
(that said the machine in TFA looks nice)