Guess you shouldn't read about what synthetic aperture radar systems have been able to do for decades... you can actually make a ghetto radar capable of capturing the data used for this demo with about $350 (in 2012) in materials. But don't worry too much. Their limitations section states that "the operating distance of a radio is dependent on its transmission power" so their system only works reliably up to 40 feet, which is true, but the dominating factor is simply distance, because any signal you get back will be attenuated proportional to 1/r^4. Pumping up the transmitted power to compensate takes a lot of energy that quickly gets you into needing operating licenses. Not to mention moving to using different frequencies that can give higher resolution of whatever you're imaging...