I've used the MotherEarth 5k coco bale and a couple other brand x and they all seem about the same. I've been getting whatever is cheapest from Home Depot or eBay. One bale, after adding perlite, fills almost 10 3-gallon bags. So I guess that's under $3 per pot. Maybe that's why they call coco "poor man's hydroponics."
Instead of trays, I used vinyl fabric under my metal shelves, attached with bent paperclips and bits of electric wire or tie wire.
This one has a bulkhead fitting, but the others just drain straight off one end into a bucket.
View attachment 1590348