More good sources for headliners are Kanter (kanter.com) and LeBaron Bonney (lebaronbonney.com) You can get a complete headliner for $150.00. I doubt you could buy the fabric for that.
The other guys are giving you excellent advise.......don't try to do this yourself, get someone to put it in. You should also replace the windlace (rope-like trim) for around the doors. You can get that at Kanter and LeBaron Bonney also. Good Luck.