Goodmark is installing sheetmetal and has a price list:

http://www.goodmarkindustries.com/HomePage.html

The link brings you to their home page and then hit installation center

Prices look good too. Why would the fluids need to be removed (a/c, coolant and trans fluid)

Are those prices common? I'm going to have to have some bodywork done in the near future (1/4 panel replacement, tail panel replacement) and I'm curious what things like that cost.

I think that those prices are very reasonable, that is if you are local to Lawrenceville, Georgia. Need to factor in vehicle shipping costs each way otherwise. Their price for R&R full quarters is very reasonable. Thats a whole bunch of work for $650. Only wish I lived nearby! :)

4) GIC is providing a basic metal replacement program. All panels will be fully welded or completely bolted together, but does not include any body work.
So they are only welding on the panels. No filling,blocking ect.
This is an estimate only and does not include or cover any labor or parts
necessarily needed to properly repair any hidden damage or inner structure rust.
Thats where it gets expensive. Once you open the can of worms. :(

Seems to be reasonable labor rates. But, no matter who does the work once you dig into a 30+ Y-O car "unexpected" problems are to be "expected".