Foose is the man, but don't forget about his competition.....Rad Rides by Troy. RRBT built one of my favorite cars of all time, the Chicayne.
If either one were to do a rendering for any car, expect no less than $500-$1000 to do so. Now, when you're ready to have them begin the project, have that checkbook open expecting to spend no less than $100K. After your checkbook is open, the next phase is the two year waiting period. Yeah, both are backlogged that far. A great deal of their projects are subcontracted, but they both oversee everything and have total creative control over the project (including the owner).
I would love to have RRBT or Foose perform their skills on my Z, but there are others that are worthy as well that are coming up in the ranks.