Meet the SQ1010 Camera Detector: a portable bug finder that you can use to find wired and wireless cameras within a distance of 5 meters. It runs on battery for up to 10 hours. The device helps you find reflective camera lenses whether they are recording at the time.
The SQ1010 weighs only 30g, measuring 3.5 x 1.8 x 0.6in. You can get it for around $20 at this time.
[where to get it]