Are you talking about one of these?
If so, there were 1000 made of those in '92. Not sure where you're getting the 43 from. I've seen people ask for some obscene amounts for those cars, but in all reality, they're really not worth much over a regular Grand Prix of that year despite their rareness. This is because the Richard Petty Edition really didn't offer anything more than some simulated Richard Petty signature decals on the doors and rear, along with key-colored crosslace wheels, and the 3.4 DOHC standard. Hell, most of the time, they weren't even well equipped (a lot of them didn't have the AQ9 16-way power seats, or a driver info center, or CD player, or sunroof, etc). Buuuuuut since it's rare, and it says Richard Petty, there are always those people who incorrectly think that car is worth a fortune.