As it seems to go every year, iPhone inventory is depleted from the Apple Store. You have to sift through wooden shelves for a single speck of a goldpagne iPhone 5S, pray to the angels for a white 5S and... well, you can actually get a 'space gray' iPhone anywhere you want. If you want to save your self a disappointing trip to the Apple Store though, developer Mordy Tikotzky made a nifty tool for you to check iPhone 5S inventory online at iPhone-Check.
Just input your zip code, select the color and carrier you want and it'll show you in which size your 5S is available (if it's available at all). It's a super quick way to check multiple stores in your area. [iPhone-Check via CNET]