About $150 to $225 per hour plus beer and pizza, depending upon where you live around the country. Problem is you will need other tools associated with body work rather than structural steel welding, that most professional welders encounter in their shops or on the job site if they work construction.
Cleco pliers and the Cleco rivets, spot weld cutter bits, a box full of assorted jawed vice grips to hold panels together, a bottomless supply box full of weld through self etching primer, and a few others that I am not familiar with because I am not a body man nor will I attempt to play one.
Most welders show up on a job site and are pointed to a work piece that is being fabricated out of parts it normally takes an overhead crane to move, or hang buy their knees welding roof joists together prior to the next floor being poured. If they have a shop it is some farmer bring in as many pieces of his broken tool for his tractor in hopes it can be put back together, or a lawn mower owner having noticed that the seat is no longer attached to his mower, and wants that fixed.
They probably do not have any more experience at joining two pieces of 16 gauge mild steel together than you do. They do own a welder (or several machines allowing them to pick between stick welding, MIG, or TIG welding along with ovens top preheat cast iron parts), and know how they all work. They have great hand eye coordination, which is important as you can not see much when you first strike an arc.
But I don't think you need a welder as much as a body shop.
I can definitely agree with Dave on the difference between the Yellow Pages welder vs a body shop. Go for the body shop.
I am not sure about that pricing though. I had thought the market for a body shop was still in the $60/hr-$125/hr range.
You'll want to call the shops and ask or maybe someone else will chime in or you may be on other boards but the metal pieces you mention seem to me to be possibly in that 15-20 hrs of work range. (depends a bit on shop experience)
Even rather than just a "body shop" you probably need to look for more of a "restoration shop". Most body shops are set up to do insurance work (body panel replacement) on newer vehicles rather than rust repair (welding in new patch panels) on older vehicles. Do some research.
Just from all that is said here and what I have read and videos I've seen...I going to take it on my self, I have plenty of room at home and I am a Engineering Mechanical Designer so I have the geometry part down, I will practice the technique on scrap metal til I have it down, I'll do it myself. Thanks again all.
p.s I will go and at least get a quote at a restoration shop near my home.