I bought out my lease for $10,700 on a 2014 with 22K miles. The value of these cars is dropping fast as the longer range EV's are poised to hit the marker. I am guessing they are starting up close to new car prices with them but I would negotiate hard on them to bring it down. If they want much over $15,000; I'd try to find a used 2014. If you plan to resell it in 3-5 years you will not probably get much for it. In buying out my lease I pretty much resigned that I will drive it into the ground... as long as the battery last. Hopefully they have a reasonable battery replacement option in 6-8 years.
They are great cars if you operate within their limitations.