I'm thinking I would offer $10,000 however it still would not be a great investment, and most cars are not. You would be way better off buying a running car that has been updated dollar for dollar.
But I can relate with the feelings that you have for this car and only recommend that you get under that car with an ice pick and check the frame and body in all the typical known rust locations. Major rust repairs would make this car a parts car unless you have the ability and time to do the repairs yourself.
Visit the Pantera Place for great information on corrosion.
http://www.panteraplace.com/page57.htm
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