The Roomba with a robotic arm is almost $400 off for Amazon’s Big Spring Sale
Beth Mauder/ZDNETIf you're a Transformers fan, I present the Roomba Combo J7+. This robot vacuum and mop combination easily transitions from hard to soft floors by lifting the mop away from carpets with a retractable arm. Also: Amazon Big Spring Sale: The 80+ deals you can shop nowThe Combo J4+ is a self-emptying robot vacuum that is also smart enough to avoid obstacles on the floor, from dirty socks to pet waste, and you can now buy it at $799 (down from $1,099).Its dual multisurface rubber brushes effectively pick…