This is a pretty good deal. The Microsoft Store is still selling it for $499. So if you're interested in grabbing one of them, this might be your chance. In my experience, factory certified typically means that the hardware is brand new. They're just doing a fire sale.
https://rover.ebay.com/rover/1/711-...%257Ciid%253A1&_trksid=p2481888.c100675.m4236
https://rover.ebay.com/rover/1/711-...%257Ciid%253A1&_trksid=p2481888.c100675.m4236