Have you checked blue book value? The market is pretty efficient on setting prices. The only thing different about buying a EV is that the battery is more sensitive to poor operation than a ICE. So you could be buying a battery that has worn beyond it's years. I agree about Leaf spy. Its a quick way to tell the real battery condition.
I bought a 2017 with 22,000 miles for US$10,000 from a dealer. Which I feel is a good deal. I think your 2016 with 80,000 miles is likely a fair deal. It's a good deal if it's 80000 km.