The total cost of all the parts in your iPhone 5S = $190.70. Apple pays a little under $10 per iPhone for manufacturing fees. The Retina display is the most valuable portion of your iPhone, and the most expensive individual part of that display costs only $28.50.
The iPhone 5S retails for $649 without a contract, and $199 with a contract from AT&T, Sprint, Verizon. There is the monthly data charge to worry about, but otherwise that's a fair price!