I have a 3 year old Neuton CE5 for sale. $200 + shipping.
I got it to do trimming around my building, but the ground is too rough for it and I always let the grass get too high. It works fine for cutting 1/2" off of the grass on a smooth lawn. I will run for 15 minutes or so which was plenty of time, but isn't robust enough for heavier duty work.
Neuton Battery Lawn Mowers - CE5 Mower | Neuton Power Equipment