;D The thing is, those items are easy enough to correct.
The fog lamp pedestals are available through Tony Branda, and the grill can be modified from a '67 version. My car also has these problems.
I had to drill my own hood for locks (following Paul's book just like the original plant workers did it), and it was easy enough -- except for the part where I screwed up and took off a little too much metal with the hole saw :-\
I see the gas caps on eBay fairly often; there's one right now and there was another just recently.
Keep in mind, however, that my car was pretty cheap. I would expect a car offered at $12,500 to have most if not all of the original, correct GT/CS items. I won't even get into the seats and the performance upgrades. While they certainly hop up performance and make the car safer (in the case of the seats), they detract from the value of the car. I don't have my price guide in front of me, but I would estimate that car's value as it sits at $10,000 at the most. If everything was corrected and the damage to the quarter panel was repaired, then it's value would probably climb to around the asking price.
-Winston