Recommend contacting GIK, here at Audio Circle. I have ten of their 2ft x 4ft 244 panels (six what they call full range and four of their limited range panels) in my 8ft x 13ft x 21ft room. Wouldn't want more. The limited range (<80 Hz) panels are straddling the front corner. The full range panels sit at first reflection points (side walls, front wall, back wall). Also have three tall bookcases, randomly but carefully filled to serve as "casual" diffusers that are along the side walls. In my practical/near ideal room, the panels honestly don't do much good, but in less than ideal rooms they provide instant improvement.
My room is well insulated (including ductwork and door that many unfortunately ignore). Shape/size was limited by ceiling height and following Fibonacci ratios. The front is dedicated to audio, the rear to an office. So room size/shape, insulation, and setup are key. Start with an equilateral triangle setup keeping speakers say 5ft from front wall and 3ft from side walls. Experiment from there.
Bass is the #1 issue in residentially sized rooms. Highly suggest reading Floyd Toole's "Sound Reproduction" to learn how speakers/subwoofers behave in-room before spending money elsewhere. In-room bass response can vary by +/- 30 dB, even in a good room can still be +/- 15 dB. The primary solution is the use of carefully placed multiple subwoofers. I have three subwoofers, carefully placed around the room. Understanding the concepts involved is the first step.
After insulating measure the room/speaker with REW or Dirac using a calibrated microphone. (Can't solve a problem you haven't first defined.) Then send all the room information to GIK to get advice. GIK uses Owens Corning 703 high density fiberglass that is the gold standard for absorbing bass. Prices for plain 244 panels are reasonable ($150/pair of 2ft x 4ft x 6 inch panels). Their Tri-Trap Corner Bass Traps start at $135 each for a 47 inch tall absorber. Recommend adding treatments a few at a time, re-measuring as you go. From your posts you're too gung-ho on treatments.
Realize that treatments/room correction are band-aids for acoustically poor rooms. Room size/shape, proper setup, measurements, and multiple subs are the keys. As Earl Geddes says: "Treat physical problem via physical means" so use room correction as a last step.
