i think the reason calmini hasn't brought the sas kit is because, they're probably waiting to see what rro, and tt are bringing out. if calmini was to bring their kit out now, and later rro & tt's versions are of better design, and cheaper it would have been a big waste of money to start producing thier kit.
either way though if you want an sas setup. it would cost about the same all said, and done. I have a design setup in my head that i would like to attempt someday. it would be toy axels with coilover shocks. if i get my hands on a set of good toy axels i will do the swap.
i think the suppliers should bring a kit to market, it won't sell to the cheap crowd, but not all of us are that way. if a good strong well designed kit were available i would buy it, and if they never come out it wouldn't stop me from building my own if i wanted too.