If you have an arduino or micro of any kind laying around, you could make a very crude cheapo DIY light meter from a photo resistor connected to one of the analog inputs through a voltage divider. The photoresistor makes up one resistor in the voltage divider, while a standard ordinary resistor makes up the other half of a voltage divider.
With a 4x 7segment LED display, "a number" can be displayed from 0-9999. (or 0000-ffff if you can read hex)
Obviously it sees some wavelengths better than others, and wouldn't be calibrated to anything, so the numbers would be absolutely meaningless to anyone else, but it would tell you which areas are brighter than others.
(I did something similar myself just to try out the a/d converters on my arduino, and to write/test simple drivers for a 4x7seg led setup.)