Get a 4X8 piece of thin plywood paneling (should be plywood, the particle board or masonite stuff will sag eventually).

Line up the paneling in the center of the roof and trim the front and rear edges to fit. The front will need the most trimming. It will fit the flattest part of the roof, but won't be wide enought to fold down to the inside "gutter". Don't worry about this yet.

Find a lightweight indoor/outdoor carpeting that you like. I used a dark brown ribbed carpet, figured the ribs would help absorb a little noise. I don't think the foam-backed stuff is light enough.

Glue the carpet to the paneling using liquid nails, leaving about 6 inches of overhang along the edges. Mine took about a quart of glue.

When the glue dries, attach the paneling to the roof ribs with screws and trim washers starting in the center. I marked the rib locations along each side and used a string to keep the screws centered on the ribs. Don't forget to cut a hole for the interior light wires and pull them through. When all the rib screws are in, trim the overlapping carpet with a razor or exacto knife so it just tucks up behind the inside "gutter" trim. It's stiff enough to hold itself in place, won't need any glue here. You'll get the idea as you go along. Cut holes in the front for the visors and their trim pieces.

Only problem I had with mine was cutting the carpet too close along one edge so it doesn't quite stay tucked behind the trim.

You may also want to slide a piece of 3/4 inch foam insulation in between the ribs and the roof. MIne already had one put in by the former owner.

It actually looks better than I thought it would, most of the time the headliner is not noticed unless it is falling down on your head.

I think this is the cheapest way to go and only takes an afternoon or so.

Art
Albq, NM