This is what I use:

https://www.amazon.com/Owens-Corning-703-Fiberglass-Boards/dp/B005V3L834

With a little searching you should be able to get a case for about $100 shipped. You'll need 5 cases to cover 220 square feet.

The downside is that you'll need to cover it with cloth. I've used muslin with good results, anything similar that breathes will do, so see what's on sale at the fabric store. The easiest method I've found for wrapping these is to cut a piece of cloth long enough to fold over and cover both sides of the fiberglass, then sew up the remaining three sides with the fiberglass inside. To finish use upholstery pins to pull the extra cloth around back.

https://www.amazon.com/Dritz-9070-Upholstery-4-Inch-30-Pack/dp/B002LN9TS8

If you have space, you can get better low frequency absorption by placing these panels a few inches away from the wall or ceiling, so hanging them somehow would be ideal.