Walmart offers the Neato All-Floor Pet / Allergy Robotic Vacuum System, model no. XV-21, for $249 with free shipping. (Amazon charges a buck more.) That's $20 under our mention from two weeks ago and the lowest total price we could find by $81. This system works on most floors and features laser-based obstacle avoidance, a 6-foot boundary marker, two brushes, and a filter that purportedly retains more than three times the amount of fine dust particles.