This article from seasoned acoustical engineer Eric Wolfram of AcousticsFREQ.com may be short on flashy pictures, but it is long on technical info and great practical advice from someone who obviously knows his business.
Pricing for manufactured, two-inch thick, fabric-wrapped fiberglass sound absorption panels is usually $6 to $8 per square foot. I have seen sound absorption panels priced as high as $12.25 per square foot! Given the large square foot area that needs to be covered to achieve a suitable home theater acoustic, this falls well outside of the average consumer’s budget.
I may annoy a few people by telling you this, but equivalently-performing sound absorption panels can be home-built for MUCH less. What follows are explanations, instructions, and specifications for how to build your own sound absorption panels.
Eric goes on to explain how to select and source the sound absorbing core material, how to build the wooden frame, how to select and install a sound-transparent fabric wrap, and how to mount the panels to ceilings or walls. [Thanks, Billy Baque!]