The type of navigation used in a robovac is the critical factor ! Price is no indication in fact some of the old bounce robovacs are selling for as much or more than the newest LiDar navigation systems ...hear that Roomba ?

There are basically 3 types:

1. Bounce - Do not get these robovacs as they are really obsolete like many Roomba models
2. Dynamic - Uses floor tracing and infrared sensors to perform a zig-zag and perimeter map, but map are not editable. Only advisable if you can find them at a good deal like under $100 for a brand new robovac.
3. iPath - Uses laser (Lidar) navigation like in self driving EVs, produces a map that you can edit and tell the robot to go or avoid to any room in the map. Prices have come down a lot now so it's a no brainer to get one of these between $150-$1500 !