No way am I spending over $100 to fix the sagging headliner of my 165k mile 98 Disco that is really starting to rust everywhere. Personally, even if I sold it tomorrow, the buyer would not give a shit about a nice new headliner compared to the rust everywhere. My truck is past the "what it looks like" stage and has entered the "trail truck" stage. In my situation, spending $120 on a headliner versus spending the money on something like a diff guard is a no-brainer.
I have never bought a car and said "wow, that headliner looks great". No one cares unless they are hanging down.
Truth is, this is a personal preference thing.