well that's not a fair comparison. the iPhone is built to be capable of doing a lot more than a Roomba, thus the cost. Also, much of the specialized expensive equipment is required for the iPhone because of its form factor. For the Roomba, the only new pieces of data one would need is a feed of the current orientation relative to its starting point and rate of travel to mapping out a room's boundaries. The logic is more complex but not to a point where expensive hardware is required.