The problem with these is that they are crazy expensive to produce and maintain. The rotors cannot be machined if they get a hard spot, groove, anything. And they are $250+ EACH. The material, just the material, for the adapters, was $500. Plus machine time.
I got new calipers, rotors, and pads this week for around $900 shipped. Add the brake lines, bracket, and adapters, and you're very close to the SSBC kit price.
Now, the guy who made these for me, Franco, has been toying with different rotors and some other bits to bring the price down, because honestly, that's where the meat of the expense is. The calipers, pads, brakelines, etc. really aren't THAT bad when compared to buying new stuff. The calipers are like $350 for the pair. Pads are $90. So the biggest expense is the rotors themselves. Like I said, he's toying with different rotors and such, but no matter what, it's expensive.
He was working on a quick upgrade for the 09+ brake equipped trucks, but when he was in the middle of that, he had to move into a new shop and I think it's been set aside for now.
He has one "kit" basically ready to go right now. I think he just has to run the adapters on the cnc mill and they're ready.