or Alibabazon.Check Apple website for refurbs.
Check BackMarket too. They sell refurbished electronics. I bought my iPad and my MacBook Air from them.
The Cherokee I fly has a stratus transponder with adsb in, so it's in the plane. If I buy a plane, that will be one of the first upgrades I'll make when the transponder is up for recertification.That should work fine. But a few times I forgot to bring my adsb/GPS device and the internal GPS bailed me out. The money you save going wifi you can put towards higher storage version.