If you already have a compliant ADS-b out system and want to add more capability with ADS-b in, a separate receiver is the way to go. More visible, more visibility.

$599.95 NZD
uAvionix PingUSB
The pingUSB is the smallest and lightest ADS-b receiver. Connected by USB to a power source and mounted by sucker onto the window, it displays via wi-fi onto your mobile device. No installation costs and using GDL-90 protocol, compatible with
Foreflight
Oz Runways
Easy VFR
AirMate
SkyDemon