It's about $6 for the part and takes about 30 minutes to replace if you're good with small screws and are careful with thin flat cables. There are teardown pics at ifixit.
Original iPhone 5s Front Face Camera 1.2 MP Proximity Sensor Light Motion Flex Front Camera with Microphone Cable https://www.amazon.com/dp/B00NGKYCNM/ref=cm_sw_r_awd_6Ln0vbEKZNV59