Enigma now makes a relatively cheap complete portable ADS-B in and out solution. I assume it works.
http://www.enigmaavionics.com.au
I understand it needs CASA approval to be legal.
I advise the owners of Enigma to take their product and manufacturing to the United States right now because time to market is everything in electronics these days.
If they do not take their product to the USA immediately Three things will happen:
(1) CASA will not approve it for years, if ever, because its made in Australia and they hate that. Meanwhile they will engage with you in endlessly expensive meetings and technical analysis. You will be lucky if this analysis does not find its way to the USA long before they consider approving your product. If you try for a confidentiality agreement, well, that will take SIx months to negotiate.
(2) If CASA do approve it, it will be with Australian CASA required changes and a CASA rider to the approval that it is for domestic use only and that means you can't use CASAs approval to sell it overseas.
(3) By the time CASA approves it there will be at least one American alternative (Garmin) and Three Chinese copies on the market and you will fail because the time to market cycle for electronics is about Nine months or less.
Message to Enigma guys: take your product to the USA immediately! Do not try for CASA approval, they don't know how to do things quickly and couldn't care less about AUstralian industry or GA aviation. You have only a few months, if not mere weeks before someone announces a similar product and if its Garmin then you are toast!