Actually I made a mistake in my post above. I meant to say "The cost of the TSO'd GPS has been the issue".
There have been ADSB compliant Mode S transponders at reasonable cost available for a while like the Trig units and others but a GPS that's TSO'd has been about DOUBLE the price of the transponder itself. The Trig unit and some others have the altitude encoder built in to the transponder
I stand by the other things I said in that post.
AFAIK the US will demand a real ADSB out even in standard certified VFR aircraft if what I read on Avweb is correct but will allow TABS in LSA, Experimentals and hopefully, gliders.
OZBUSDRIVER, how did you come on the information about the Enigma timeline? I sure can't find it on their website.