I went to check it out and it looked the business so I bought 3 bags. So for anyone wanting to give Boon mix a go, you can now get all three main ingredients commercially in Australia

Now for the bad news...the bags were $20 for a 10kg bag...which is pricey (more than Akadama, which comes from Japan!), BUT it was sifted, usable straight out of the bag so kind of like buying loin over rump, you get to use every little bit!
I have had great success using only Akadama and Pumice, so I'll trial 1/3 parts next season.
Washed to remove surface powder but unsifted straight from the bag.