Ziegler or Granger is where you should get it.
Both Ziegler and Granger prices match when you break them down by months and deductible, you should save more than half based on Mopar offering. I got mine from Granger, it worked perfectly, it showed up on my Mopar Dashboard with all my terms, saved a ton of money over my dealership and Mopar direct.
There are a couple of threads that cover both places, I think both are brick and mortar dealerships that offer the Mopar Maxcare warranties at heavy discounts and make money purely on volume.