Did you check the 2004 down in the Buy/Sell area?
The headliner WILL come down on ALL coupes. Nothing can prevent it. Many on the forum have already replaced theirs. It runs about $150 if you remove the headliner and re-install after it's been relined.
That said, the seller should have told you what was wrong with the car before you made the trip. He not only wasted your time, but his own time, and only set you up to be disappointed. Whenever I sell a car, I make sure I tell every little thing that is wrong. That way, if the buyer still comes, he will not be disappointed, and really has no ammunition with which to throw at you.