Buy.com has the iRobot Roomba 510 Vacuum Cleaning Robot for $159.99 with free shipping. iRobot Roomba 510 Vacuum Cleaning Robot features the newest innovations for dramatically improved performance, reliability and durability. It systematically cleans three rooms on a single charge, gets into hard-to-reach areas like wall edges and beneath furniture while avoiding stairs and other drop-off. Roomba automatically adjusts from carpets to hard floors and back again. Improved Virtual Wall tells Roomba where to clean by restricting off-limit areas.