I found pine bark fines in Marietta, Georgia!
I have no affiliation with this company -- Wood-Tech out of Canton, GA -- I just wanted to share that I have successfully used their soil conditioner *AS-IS* for the pine bark fines ingredient in Al's 5-1-1 mix!
Since it is made of fully composted pine bark fines there are some small particles (maybe 15%) so I cut back on the sphagnum peat ingredient a little bit.
I bought this product labeled as "Aunt Nancy's Soil Conditioner". I don't know whether this is a stock or custom label. The distributor's website mentions that they offer private labels. I bought the product at Rick's Farmers Market in Marietta, GA.