There are several guys that have described their light box measurement contraptions... Not sure what your definition of cheap is, but I'd expect to have to pay at $100-ish to get set up. I think unless you're going to create a website where you compare a large number of lights against one another, it probably isn't worth the hassle or cost... I mean, if you have two lights and you like both of them and you want to know which is brighter, there is a thing called a ceiling bounce test. You just aim the light up at the ceiling which will the reflect off and illuminate the room to one degree or another. Then do the same with the other light. Whichever one lights up the room the best is the brightest. The reason we bounce the beam off the ceiling is this will give us a lot better idea of the total output or 'lumens' which is quite difficult to accurately guesstimate while just shining the beam on the wall. From two or three feet, the light with the highest 'lux' count will almost always seem the brighter of the two but for lumens, you need to take into account every single bit of light in the hotspot, the corona, the spillbeam and how bright each of them are.
As for throw, that should be VERY easy to compare without any type of test equipment. With the throwier lights, go to a reasonably dark parking lot and pick a reflective object... compare two lights and whichever illuminates the reflective item best is most likely the light with the most throw.
Personally I wouldn't mind having a basic setup, more so I could accurately test, plot and compare runtimes between lights than just compare brightness or throw. I never get tired of going down to the church parking lot and comparing two or three lights.
Get to meet quite a few nice sheriff deputies that way too!
