There's a "special" reservation page you can check in the morning (times vary) where you can reserve a phone for same bday pickup if they have stock. The page and checkout options will indicate it's for the iPhone Upgrade Plan - but you *can* flat out buy it cash once you get to the store.

The "special page" shows inventory right now - the "normal" one does not. They're giving people in the upgrade program a leg up (they sent an email with that link if you're in the program.) The "normal" page is for normal schlubs unless you got the link somehow.

The "special" page is: https://reserve.cdn-apple.com/US/en_US/reserve/iPhone/availability?channel=1&iPP=U

The "normal" page is: https://reserve.cdn-apple.com/US/en_US/reserve/iPhone/availability?channel=1

And the upgrade program might be a better deal (if you plan on buying Apple Care anyway) because it's a %0 interest loan that basically pays for half of the cost of the phone when upgrading. But you also have the option to just pay the phone off and then sell it on the secondary market if you think you can get more money that way.