Suitable for lawns .75 acre and below. Works great, I have used it for 2 years now.
Price is negotiable. Cash preferred.
It is essentially a roomba and you set up a wire around the edge of the property. This model can handle multiple areas with concrete between them. Comes with charging dock and wire. It moves randomly, will not really create stripes, but it keeps the grass short without worry. Works even in the rain. You set up a password that protects it from being stolen. Rain, snow, does not damage it.
Being honest, setup is a bit frustrating at first, because if the wire is too high up the mower will cut the wire by accident and stop. Takes a while to troubleshoot those breaks in the line, but once those trouble spots get resolved, it is great and there are usually no more issues. I think every robot lawn mower has these issues, though.
If you hate mowing the lawn, it's fantastic and well worth the money!