Where can I find some of these bad boys? Each door panel is appx 9". Specifically looking for unfinished, full louvered that we will stain and poly to replace existing nasty painted ones in a small condo.

36" openning, could you just use a set for a 36" door (2 18" panels) and have it open to one side, or remove the hinges for an 18" door opening and hinge it to one side of the door opening?

If you absolutely need 9" panels, probably any home center or lumber yard could order them for you.

If time is of the essence, get a 24" door set, which is 2 12" panels. Rip one side of the door on a table saw to remove the side stile. The slats are free floating and will slide right out. Cut them down with a miter saw. The top, middle and bottom pieces can be trimmed to the correct length using a skill saw or jig saw. Place the pieces back together and use wood screws and glue for the stile you had removed to re secure it to the rest of the door assembly. Predrill a hole large enough in diameter to get the screw head sunk about 1/4" below the surface of the style. Use glue and a wood plug to cover the screw location and sand smooth. Time wise, it's not too bad of a project, couple hours for a couple of doors, whereas who knows how ong an order will take. If you do it that way, you can even sand and finish each louver piece individually.