1980 Camaro rust problem, how to go about fixing this?
 

I just bought a 1980 camaro the other day and I have found that there is quite a bit of damage to what I believe is the rear valance from rust. I brought the car to a mechanic friend who does body work and he said that they could fix it for approximately $400-$500 because of having to drop the fuel tank to fix it. They would also fix a palm size rust hole in the sub frame as part of that price. I was just wondering if this is a good price for this to get done. Also, what would be my best option? I have attached a picture.

If they can fix it right, that's one heck of a good price, even if they only prime it when done! I wouldn't mess with it myself for that kind of dough!

Ok. They're goin to put it on a lift Monday and look at it more to give me new of an exact quote. Hopefully it won't be a lot more. What is the name of the part? And if worse comes to worse and I can't afford gettin them to fix it how can I go about fixing it myself?