Thanks for your info. I intend to follow your example when my run flats need replacement. I was at Costco today, and their price for the Michelin Pilot Sport AS+ is $269.99. This includes mounting, balancing, and rotation for the life of the tire.
I checked with Costco and they gave me a bit of a hard time about replacing run-flats with non-run flats without a spare. I don't have a spare, so am at the mercy of the road and would have to call AAA with a flat. Some folks say they are carrying the tire-seal product, but I believe the Discount Tire warranty is voided is the premature flat is "fixed" with a tire seal product. Anyway, all food for thought.
I replaced my run flats 3 years ago and ran 45,000 pleasurable miles with a can of fix-a-flat and an electric powered air pump in the spare tire well. Never needed to use them. I just replaced those tires last week with another set of non-run flat tires. Couldn't get me back into run flats for anything. Porsche does not equip their cars with run flats or spares. Just an air pump.