If the Roomba's $300 price tag is too rich for your blood, but you're still on the hunt for a lazy way to clean your floors, OCedar's roving, spinning O-Duster might just fit the bill.
At just $40 the price is right, but there are other costs you have to consider. Namely, that this is about as far from a Roomba as you can get. There's no AI to speak of, so it will literally just randomly wander around your floors. But the rotating drive train at least ensures it won't get stuck when it encounters an obstacle. And instead of a vacuum, you have to rely on disposable electrostatic cloths to collect dust and dirt.
On a full charge it will run for almost two hours, which is definitely a feather in the O-Duster's cap. And as long as you don't have pets or kids dropping endless mounds of food and dirt on the floor, this might actually be a decent low-rent alternative to smarter robot cleaners. [O Cedar via Home crux]