I just bought an SLK55 from Carvana. 7 day right to refuse, 100 day warranty, delivered to my door. Right at KBB. What's not to like? Certainly, I had no more opportunity to kick the tires than with the 20 that came from eBay, and none of those had a warranty.
My son sold his Prius to Carvana, got more than any dealer would give him on trade. They sent a truck to pick it up, and handed him a check.