Just be aware that if the exceptions go away ADS-B out will be required above 10,000 feet after 2020.

if you have a transponder you will need to purchase an approved GPS source that currently costs about $3000 with installation.

if you don't have a transponder then you will to purchase and install a transponder as well for another $3000 or so.

Also as I understand it the 150Watt Mode S transponder such at the Trig TT21, will not be acceptable after 2020 to meet the ADS-B out. So even if you have a transponder you may need to purchase another one.

of course it is possible that the FAA may just modify the exceptions and allow only a transponder or 150W transponders or currently non-approved ADS-B out sources, or some other modification.

The FAA currently says it is ok to install non-Approved GPS source for ADS-B out in experimental aircraft, but is unclear if this will be acceptable to use above 10,000 feet or not (seems like probably not)

Brian