I just traded a few emails with Geremy who works for Appareo. He told me that the factory does NOT require a dealer install and that they are fine with an A&P install. They leave it up to the discretion of the dealers. So, you just have to find a dealer who is willing to sell you the $3000 transponder without mandating that they also gouge you for the install.
I did assist my A&P with the Appareo install in my 180 and it was extremely easy, as was the ADSB check flight.
So to anyone who is considering going for the rebate, I highly recommend this route before the rebate program ends in September.
Chris

Garmin is doing the same thing with the GTX-335 and put together a promo kit that includes the WAAS GPS antenna. I'm sure their plan is to compete head to head with Appareo. My Garmin ran 3k from Spruce with a 4 foot wiring harness made up by their shop. Competition between brands is starting to pay off. That's good for all of us.

Rich