Sourcing stuff locally should be a very high priority. Not only in money saved in shipping (A LOT!), but just being able to scoot down to the local HD, Lowes, or Feed & Seed store instead of the week or so lag time involved in ordering online is a huge plus over a grow season.
Like
@kratos015 mentioned, a lot of stuff is either redundant or, superfluous and there are very few items where nothing else will really do. Kelp meal is one of those, Neem meal/cake is another. But, for most needs like N-P-K, minerals, etc., there could be 5 or more different sources and the local one will work just fine. Sadly, the local products are usually not very glamorous or esoteric and the inexperienced will spend 5x, or more, for say, high N guano from the purple tailed, goggle eyed Hindu Kush bat (I made that up), rather than plain old blood meal from the local store because some internet guru gave the bat a shout out and nevermind that both are functionally equal. The bat sounds cool, the blood does not.
Is the pumice local to you? I ask because the sources for it are 2k+ miles from me and very expensive here. I'm in the foothills of the Smokey Mtns and we simply never had the 'right' type of volcanos. Perlite however is very cheap and it's all I've ever used. It's ~1/5th the cost of pumice.
I use dolomite lime for fresh mixes and later reamends with Ag (calcitic), lime. I had Mg deficiencys using just Ag lime that did not occur with the dolo. Ag lime is the functional equivalent of OSF and is much cheaper and easier to source locally. Not as common as dolo, but still, easy enough to find. The Mg in the dolo lasts a long time, longer than the Ca, so, just using it when first making a mix takes care of the Mg for several years.
BTW, glacial rock dust is Ok, 1cup/cf is fine. Leave the powdered humic where it is, the fresh worm castings will provide all the humic acid the soil requires. Adding more just causes problems. Treat stuff like that like steroids, very, VERY little is needed for results.
Wet
