5K for a headliner. Was it a buy one headliner at regular price, I'll throw in the car for free. In 1980, you could buy one heck of a used car for 5K.
I did it myself on a Mustang. Not that hard. I personally recommend pulling the windshield and backglass before attempting. Gives you opportunity to fix any rust issues plus the headline comes out looking better IMHO.
You might want to ask if the 6 hour job includes pulling glass.