If you don't buy a blade balancer, it is still possible to balance the blades using a dowel or other method, but a good blade balancer makes the job much easier.

The KSJ-528 blade balancer works well. The Koll Rotor Pro is better than the KSJ-528 but is overkill unless you're doing advanced flying.

I highly recommend CAing the tip of a sewing pin to the pointer of the KSJ-528 to make the scale easier to read.