If ur willing to DIY, you can buy venyurecraft godap for iphone 3gs for 20 dollars (msrp 200). All you need to do is saw off the sides so it fits the iphone 5s and an adaptor to convert 30 pin to lightning. It has better form factor with iphone 4s though.
I would also consider ibasso. Their d zero is a little over 100 but has great form factor with iphone