We typically see them going for 75-100 each in the condition you posted. Once as high as 250. Just depends on timing, someone out there has seen only junk and yours will look like treasure.
We have done a gas tank and a radiator. If I remember, correctly, it was much cheaper than new. I think the tank was 125.
What fifth group restaurant is in Marietta? I know the original el taco is fifth - I would go there everyday if I lived nearby.