You can find it on ebay, whatever it is, but if you accidentally leave it in the bus station, or drop it in an alley, or God forbid, deliberately put it where people can see it, jumpy citizens and humorless bureaucrats will find it, fear it and over-react to it. Emergency personnel will be called in to examine it, evacuate the area around it, cordon it off, and eventually blow it up. Cities will grind to a halt around it, no matter how mundane or benign it might be. Authorities will assume that it is an infernal machine and will spare no expense to try to protect us from it.
