Rich,
The GDL39 is definitely one of the best priced products Garmin has offered. This issue it that is it only compatible with other Garmin units, actually only the 795/796. Both prices over $2k.
They will not integrate with us or other GPS units or app. I suggested they are limiting safety and holding back the benefits of ADS-B. Garmin portable units have really slowed down due to the pricing in the market. I contacted Garmin to work with them to integrate the GDL-39 with the iFly, they said "no we are not integrating with other brands".
I think the reasonable GDL-39 pricing is to compliment their 1090 ES upgrades for ADS-B out. They don't have an affordable ADS-B Transmitter option, so they have to make the receiver (GDL-39) affordable to offset the overall ADS-B In/Out costs. What pilot would want to pay for ADS-B Out, but not be able to benefit from that data others are sending out.
Additionally, they need a ADS-B receiver to mate with their Pilot App to be competitive. What would Garmin look like if they have to use a third party piece of hardware to complete with the ADS-B demand.
No doubt it is a nice unit, but it has limited use in todays market. I personally don't really see Garmin opening up to integrating with other brands and Apps. Just my two cents... probably only worth about a half cent.