From what I read on the KT website, they're not selling them right now. Something about supporting a movie called "Meet The Gang" (which seems somewhat interesting). I also hear that they might be under ATF investigation. Don't know if that's true or not.
Based on what I've read here and on the ATF website, it's perfectly legal to build your own from an 80% receiver, you just can't build it with the intent to sell it (not that you can't later on, depending on state law). Is there anything wrong about that statement?
Also, if further down the road you were to decide to sell it, would you need to add a SN and manufacturer marking to it prior to sale, or would it be good to go in its current "blank" state?
Finally, since KT doesn't appear to be selling the 80% receivers, where else could I find one? I've seen the DSA website where it's < 80% complete for about $25, but I'm not aware of what kind of work needs to be done to it, and I'm hesitant because I don't have access to a milling machine.