I always balance my planes on my fingertips. I've checked this method against the CG machine that I own and have always been close enough that I don't bother using the machine. I certainly wouldn't spend the money for the Deflection Meter. That's simply a useless "gadget". You can accomplish the same thing by holding a ruler at the trailing edge of the surface, or if you're anal about accuracy, hold one of the clear protractors out at the tip.
Dennis-