2 FOR IROBOT Roomba 500 HeavyDuty 510 537 560 580 630 780 880 Ni-MH Battery $49.98 - PicClick AU
Amazon.com: iRobot Roomba Authentic Replacement Parts - XLife Extended Life Battery - Compatible with Roomba 400 600 700 800 Series Robots : Home & Kitchen
TATTU 4500mAh XLife Extended Life Replacement Battery for iRobot Roomba | eBay