I've been using a bit of perlite lately with potting up plants around our house in my potting mix. The 8qt bags of Miracle Gro are on average, $5-6 each at my local big box stores and has been a bit spendy buying multiple bags. I sought out a local garden supply store about 30 minutes from my house and picked up a 4cu ft bag for $15. Figuring ~6.5 gal dry / cu ft... bulk = 15Ã‚Â¢/qt whilst the Miracle Gro bag is 75Ã‚Â¢/qt. That's quite a difference.
Can save you a grip buying in bulk! Imagine this bag will last us a while.