Grab yourself a dumbbell set. Find the heaviest weight you can hold with your arm outstretched. Mark a line on the wall so you can check the level. Repeat several times. Note the weights and any wavering of your arm. Maybe add the time you can hold the weight.
Add Power Balance. Repeat the above. Note the weights and any wavering of your arm and time.
That should give you a measure of the effectiveness of the Power Balance thing in terms of kilograms.
Ideally you should test a number of people including convinced, sceptical and don't care.
F@ck it. I'll just buy one and do it myself.

... not at $60 I won't.