Appareo is a good place to start for those of you who do not have a panel mount WAAS GPS Navigation system in your stack and if you have a tighter budget. Many of you out there already have some sort of STRATUS ADS-B IN device such as the STRATUS IIS so all you have to add is the ESG Transponder and a kit to interface your portable STRATUS device with the ESG ADS-B Out Transponder and your done. Simple complete ADS-B IN/OUT solution for minimal cost.
Avidyne has the AXP 340 ADS-B OUT Transponder that when interfaced to a compatible GPS WAAS Navigation system also meets the 2020 ADS-B mandate. See more info on this unit and other ADS-B options available by following the link below.