Is it easier to repair Iphone 4s Screen or Replace it?

I shattered my friend's Iphone 4 screen and I don't think she has insurance on it. Is it cheaper to replace her screen or buy a new iphone?

Added (1). Is it Easer to Repair Iphone 4 screen or replace the phone itself?

I bought a 4s recently for $65. It's refurbished. I don't know if you can repair it yourself. Check YouTube for repair videos.