These tools are nice to have, but as others have stated you don't need them right away, I still balance my 35-55% models by finger with the help of a buddy of course. I do personally use a deflection gauge when setting up my control surfaces, its just faster when setting up triple rates and keeping everything very accurate, but again it's not one of those things you must go out and get before you are able to go flying. I will say this, if you are into competition pattern or IMAC flying then the deflection gauge is a good tool to use for setting up your airplane otherwise spend your money someplace else.

Bob