That was 10 years ago! I have a vague, probably inaccurate memory, that there was a hitch in getting the stuff made, so it was dropped. There were a few other attempts by the very experienced planted tank keepers, in Europe, I think, to make an equal, but cheaper alternative to Aquasoil. I'm pretty sure none are now available.
I've experimented with many substrates over the past few years, and my conclusion is: just go with the Aquasoil. Its ability to grow plants consistently is unmatched. Sure, it costs a bit more upfront, but honestly I'd rather pay the retail price than waste time and deal with the mess from home-made concoctions that may not even work.