I sold my Mercedes GLS 450 via Gurus to a dealer for more than the lease buy out. Very smooth process with multiple dealers offering good deals because they have customers already lined up.They are buying and selling directly to car dealerships. It's a way for dealership to get access to used inventory. It's not available in all states yet.
I do have to highlight though that all I have at this point is a quote. I have not gone through their process yet, so take with a grain of salt.
Putting my 2018 5-seat MX on Gurus tonight to see if listing there can beat the Tesla, Carmax, Carvana, and Current offers I have. My EDD is March 17-22.