Measuring light hum

Fluorescent lights are notorious for modulating their light at a 60 (or 120) Hz powerline signal, which bothers some environmentally sensitive individuals. Incandescent lights are much less prone to this problem. Depending on technology, LED lights may be free of this problem because they convert the power to a filtered DC before powering the LED; Other LED light sources may just pass on the AC signal.

Is there an inexpensive meter that will measure the amount of hum in a light source for environmental evaluations? Or do I need to design and build one? (simple in principle - all I need is a photodiode or photo resister, an op-amp, bandpass filter, and a meter). I really want a COTS (commercial off the shelf) solution, but If I designed and sold such a unit, would there be a market?