Agway is a nationwide chain of farmers supply stores. Lots of garden centers are also authorized dealers.
You mix, if I may critique it, has a couple problems.
-Needs more lighteners
-The manure and topsoil are both kinda wild cards. MAnure- what sort? Has it been composted too? Topsoil could be pretty much ANYTHING, lol.
The deal with that Agway product is that it is very very consistent and the pH is in range and buffered there.