Acoustic treatment question: do you agree with Dennis Foley that $46k to $65k is required?

That price for activated carbon above is totally out to lunch. Activated carbon starts at about $0.5/kg.  Let's they need a specialty grade so 10x maybe. They aren't buying it on Amazon.  Only highly refined scientific grades would be the cost quoted above.

Well, I am truly in need of more education. My room treatment cost less then 0.5K

Lemonhaze. I measured the room response with a small omnimic and cell phone. I was fortunate enough to build, change, add, subtract, listening and listening again as I worked through the build process. This gave me the ability to hear what worked and what didn’t. My ears guided me. (I’m now diving deep into room measurement tools/ software.) and yes it measures great down to 30hz. 
A small room needs about 800-900lbs of activated carbon to provide meaningful results. I paid $165 per 50lb bag of coconut shell activated carbon. Just as a reference.  
I agree that not everyone will spend the amount of time building out their own room, as I did. From a few acoustic panels to a world class music room, the important thing is we enjoy our time relaxing and listening to great music. Every room is different and will likely require a unique solution. 

I wouldn't waste five minutes on Foley's follies.  Period.  Just move on from him.

Just establish your budget, use REW and a good USB mic, begin with very low and low frequency mitigation, then first reflection treatments, starting with side walls and rear wall.  Determine which products you can afford to purchase or that you can DIY, based on proven design effectiveness.  Finally, determine what compromises you will have to make in terms of budget - what you can live with or be satisfied with.  

@ shalommorgan, thanks. If you have tamed those wobbly waves down to 30Hz then your room should sound as good as it looks.

I will send you a PM shortly.