With the popularity of the iPhone 5S, they are just hard to find when you have an exact model, color, and carrier in mind. I found http://www.tradeinhappy.com/get-iPhone5S-sell-your-used-iPhone that fixes this entire issue.
On the home page of the website, you can search for store inventory using a simple search engine that allows you to enter options for color, carrier, capacity and other options. You can narrow the store search by zip code and mileage proximity.
I tried a search and the results were amazing. The search results showed me a Google map with the exact stores pinned so I can go right to that store and purchase my iPhone 5S.
Bottom line: If you are looking for an iPhone 5S, you need to go to this website first: http://www.tradeinhappy.com/get-iPhone5S-sell-your-used-iPhone