ok, why are 360 flywheels so expensive

Why so expensive?

It's simple manufacturing economics: Chrysler made one 360 flywheel for every several dozen neutral balance wheels.

Add in the extra cost and machine time to make one.

There are many alternatives and as stated, don't skimp on flywheels OR their attaching hardware.

The blue print is readily available, ANY decent fly wheel shop can match the neutral balance wheels to the print.