One forum member, just one, reported successful negotiation of end of lease payment with dealer. My dealer asked me what I would pay and only promised that he would see what he could do. When I said $15K, he said, no. Many dealers won't even try as they would rather you lease a new car from them which is what I ended up doing.
There is no question that they get rid of our cars at auction at around $15K or lower as I saw my old car on cargurus.com listed for $18+K. If you know someone who knows when the auctions happen, you can try to buy your leased car back then.
Jeff in NYC
MB '17 B250e; MB '06 E500W; MB '81 380SL