Please download the confirmed BOM here:
First try to have a working vocoder in the 'basic configuration' without the voiced/unvoiced option enabled.
The $ 99,95 version, I thinks it's level 4.
The capacitors used on the spectrum analysis are all from TDK. Not the cheapest, but I am satisfied with the result.
I've used some of them randomly with no significant issues, but in one of the prototypes I've built the 741's were picky.
The less residual voltage, the better.