Chiming in late here, but hey, I have a couple extra minutes... (Of course, there's been tons of previous threads about this if you wish to use the search function. One of the threads even has the pre-, during, and post-paint pics.
My paint was $7500. It's not the materials that cost the money. It's the time and skill involved. Once your car is painted, you'll be doing the same thing everyone else with a C3 does...
The paint shop has to be careful about sanding fiberglass 'cause it ain't like stripping metal. IIRC, it needs to be sanded by hand. Media blasting or chemical stripping can be done, but it's risky on fiberglass, especially one a 43 year old car. When they are sanding down the body, they need to run along the creases and NOT over them, side-to-side. They'll destroy those crisp edges on the fenders right quick! It's pretty easy to tell C3's that have been repainted because the fender lines are smooth & rounded, not crisp & sharp like they left the factory.
Then there's simply the time invovled to disassemble and mask off everything. Door panels come off, glass come out to get to the mirrors. Hood comes off (if you plan on getting the underside painted). Trim pieces, logos, gas cap, etc... There's a LOT to mask off and/or disassemble. Once the car is all prep'd, painting it is the easiest part of all of it. Then all the pieces have to sit for a few days while the paint cures. Otherwise you'll end up with depressions in the paint where the touching pieces emboss the paint.
Keep in mind that there are plenty of people that will be very happy doing it themselves, or claiming they got a show-quality job for $3000 or less. That's your decision which way to go. Caveat Emptor! You're the one that has to live with the results. Have you settled for anything on your car? Or have you always got exactly what you wanted because you didn't settle? Food for thought.