Following record opening weekend sales following the launch of the iPhone 5s and iPhone 5c, Apple has extended in-store collection to both of the new phones. This means that before heading out to find an iPhone 5s, you're able to hit up the Apple Store online, check stocks, and reserve one to collect in person.
The iPhone 5c is generally speaking more widely available, which isn't surprising since Apple confirmed just this morning that the initial supply of the iPhone 5s has sold out. But, it looks as though some versions on some carriers are starting to come back in stock, so if you missed out over the weekend head on over to the Apple Store website right now and take a look.
It does appear to be a U.S. only option – following on from the Chinese pre-orders following this method – so if you're elsewhere in the world you'll have to visit your local Apple Store in person to see if you can buy one.
Source: Apple Store