I found a place an hour away that sells Pro-Mix BX 3.8 Cu ft. bales for $28.5.
http://www.greenhousemegastore.com/product/pro-mix-bx-38cf-compressed/soil-growing-medium
Unfortunately, they're a mail order company. The shipping on a 3.8 Cu ft. bale is over $40.
I emailed them to see if I could buy some and come pick it up on site. Hopefully they say yes...
For some reason they sell 1 Cu ft. bags of pro-mix for $18.
That size bag is $6 at Menards. It doesn't make any sense that the 1 Cu ft. bag is absurdly expensive while the 3.8 is really cheap. 1 Cu ft. for $18, or 7 Cu ft. (loosened) for $28...