I would agree with this.
The problem with paint work is all the variables, and peoples interpretations.
For instance you say you dont want a show car, but no earl schieb.
What exactly does that mean to you? What is your definition of a show car?
Are you looking for an OEM finish, smooth as glass? No tape lines, etc,etc?
Secondly is the amount of bodywork required is a huge variable for cost. Cars that are straight dont need filler and primer work, cars that have dings/dents take time to make them straight.
Material will also play a huge roll in cost. Some material is more than others, you typically get what you pay for. Color will also play a factor in cost. Some colors are more expensive than others
Also how you go about it will play a factor in cost. What I mean by that is are you going to have the shop do all the R&I's (Removal and Install) of the bumpers, trim, locks, lights,etc? Or do you want them to just mask them off?
The body style will be a variable. There are way more parts for a 87-up GT vs an LX. Convertibles have more trim to remove,etc.
If you're paying a shop start to finish, you'll be in the range of $2500-10,000 depending on what you start with and how nice you want it. Realistically $4500-$6500 is probably where it would fall if you are having them do the R&I's and making it an OEM finish.