Looks like Apple has stopped selling the iPhone 5s as the device is no longer listed on the Cupertino-based company's official website. A quick looks reveals that the phone has been replaced by the newly-launched iPhone SE.
While we are yet to hear an official confirmation on this, the discontinuation shouldn't really come as a big surprise given that the iPhone SE not only looks almost exactly like the 5s, it is of course comparatively more powerful as well.
Released back in 2013, the iPhone 5s was powered by the Apple A7 chipset and sported a 4.0 inch (640 x 1136 pixel resolution display). It featured 8MP rear and 1.2MP front unit, and was available in 1GB RAM and 16/32/64 GB internal memory configuration.
Third party retailer such as Amazon are, however, still selling it.