I bought a used car last year for 13k after taxes and fees. 9 months later, I sold to Carvana for 16k (even with a few scratches that would have been $300 to fix, plus a $200 scheduled service coming up in a few weeks). Carvana needs to make a profit, so presumably they're going to mark it up further. It's a crazy world right now.
Carvana is the Internet's BHPH lot. They don't care how much they spend to buy the car because they're gonna sell it for 50% down with 20% APR to someone who can't get financing otherwise.