So you have spent a lot of money on your diy quadcopter(or any multirotor) and refuse to give any more, but you still need a propeller balancer. Balanced propeller is very if not the most important thing for multirotors.
Guess what, you can make your own, from old computer components.
If you happend to work in ICT company, there is always a lot of that stuff around. Besides broken hardware, some tools may also come handy. Let's begin with stuff you are going to need.