While I only see one Monsanto product (MG), I would have to agree that one is still too many. I like coco coir instead of vermiculite, but peat or rice hulls will work too. And I don't like perlite. I still have some old stuff left in my soil, but I add expanded shale or expanded clay pellets these days instead. Perlite floats, and will float right out of your soil. Completely defeating its purpose. You are also lacking trace minerals found via rock dusts. Make sure your sand has some nutritional value like crushed granite (silica) or even better greensand (ancient marine deposits - all sorts of goodies).
Something like
2 parts compost
2 parts peat/coco
1 part expanded shale
1 part greensand
with about a cup of azomite or glacial rock dust per 3 cu ft would be a good start
If you want to get a little fancier, add some
dry molasses (food for microbes)
neem cake meal and crab meal (pest deterrents)
beneficial nematodes and some kind of myco
If you are trying to do this cheap you can create your own myco colonies using Korean Natural Farming techniques
www.prokashi.com/videos for tutorials and explanations
Lots of other goodies can be added and many are wonderful, but something this simple can serve you well.
