Wait, NRC values are ratings of the ability to absorb frequencies from moving through it.
*Thank you* for correcting my misunderstanding of NRC. I thought it was a measurement of transmission across a barrier, as this is how the term was used in many, many threads on here when I was building my studio in 2006.
I'm not talking about using a moving blanket as a broadband absorber, but as bass trapping in corners. Have you used moving blankets? They deaden and absorb sound really very well. It's not 703, but it's much better than foam if used thoughtfully. Someone with a roughly cubical room like the OP is gonna need a lot of bass trapping, and it sure can't hurt. I'd take a blanket, fold it lengthwise three or four times to make a thick rectangle, and hang it from the short end of the rectangle across a room corner. Then see how it does.
One can use cheap stuff + their ears to understand and tune a room. That's what I did. You need your ears to tell you whether the expensive stuff is working, too.
"Trying some common cheap solutions and listening to whether it works" is very different from "Try whatever and hope it works."
Dense material like moving blankets is going to get some decent bass trapping started for the OP. Professionally produced bass trapping is $$$ and in my experience, it's good to get started with things like moving blankets and a staple gun to see how it works in your space. Then build some 2" 2'x'4' 703 panels and a few 4" panels for the corners. You can use the moving blankets later to isolate things in the studio (temporary vocal or VO booths) or even to move things! That's what I did, and got a room to sound pretty good.
No need for that to "kill" ya!
Your NRC definition is again appreciated. I hate to be the victim and subsequent perpetrator of misinformation and misunderstanding.