eBay with 1SaleADay has the iRobot 581 Roomba Cleaning Robot Vacuum for $300 + $0 shipping = $300 shipped. Features a 7-day scheduler, wireless command center, 3-stage cleaning, and Dirt Detect technology.
I can't speak for the roomba, but I do have the Neato floor cleaning robot, and it works amazing well. It uses a rotating laser to map the room as it moves so it knows where it has and has not been. Works quite well and has one of the most powerful vacuums motors... in my old house, it managed to consistently remove dust and hair from the carpet, even after 3 runs in a row. I do have a Scooba and it worked ok, except the horrible battery it comes with... do not replace with iRobot's overpriced, short-lived battery. This swayed me to Neat...
I have a hard time believing that these things are worth a flip...
You can find a nice used one for about $25 - $35 at thrift stores...
I use one whenever I can. They work great. It vacuums more often then I would on my own.
In order for these to be useful they must be used every day as opposed to once a week.
I can't speak for the roomba, but I do have the Neato floor cleaning robot, and it works amazing well. It uses a rotating laser to map the room as it moves so it knows where it has and has not been. Works quite well and has one of the most powerful vacuums motors... in my old house, it managed to consistently remove dust and hair from the carpet, even after 3 runs in a row. I do have a Scooba and it worked ok, except the horrible battery it comes with... do not replace with iRobot's overpriced, short-lived battery. This swayed me to Neat...