I am curious as to what part of the country you live in, and wondering
if it may be a "local" shortage there.

I'm in SW Ohio. As I said, 10 years ago, all the big stores and
hardware stores had bags of composted cow manure this time of year.
Right now, I only found one small garden center that carried it, but had
sold out, and Meijer, where I ended up getting bags for $1.19 each.

All the other places only had bags of topsoil, humus, "humus with
composted cow manure" (but didn't tell how much of each), and mulch.