It has never been more confusing to buy an iPhone. It's not Apple's fault — it's this way with every phone right now. Rather than just having two purchasing options, you now have to navigate between paying upfront, buying a phone in installments, upgrade plans, and plans that fall somewhere in between each of them.
More options means more confusion and more flexibility
But the bright side of all of this is that you actually get some interesting new options for how to buy a phone. These aren't just new ways for cell companies to take more of your money (...for the most part). You now have easy ways to break up the cost of a phone or to switch to a new phone every year — sometimes even more often.
Here's the deal with buying an iPhone 6S or 6S Plus: it goes on sale Friday, September 25th. It'll be available for walk-in purchase at most Apple Stores — Oregon, Delaware, New Hampshire, and Alaska not included — and likely many carrier stores and some electronics stores as well. If you want to get one in stores on day one, you'll want to arrive early. The iPhone can also be ordered online for home delivery, which is probably going to be the simpler option. Unfortunately, you won't be able to order it for first week delivery; at this point, it's sold out until early October.
Now the question is which method you're going to use to buy the phone. If you're in the US, we've tried to make this as simple as possible with the flow chart below, which breaks down the costs and options and what you'll get from them. One thing to note: we recommend buying the 64GB model of the 6S and 6S Plus, which costs $100 more than the base 16GB model. As such, all of the pricing below is for the 64GB iPhone — you'll end up paying more or less if you opt for the 128GB or 16GB model.
Update September 24th, 7:18PM ET: the flowchart has been updated to reflect that Verizon is now offering an upgrade plan for iPhones. It previously was not offering any new upgrade plans.