Hi Fossil man,
I could be wrong, but as far as I know none of us regular contributors deal in fossils, so I'm not sure how we could price your fossil. Having said that, nautiloids similar to yours often appear on e-bay, maybe starting at $20 or so. I really don't think it is especially valuable, I'm afraid.
Any chance of a larger picture? the picture you have posted is tiny and it is hard to make out what is going on.
From a casual look at Google it seems that one of the most common nautiloids from Caesar's Creek is
Orthonybyoceras(aka
Treptoceras), an orthocerid nautiloid. If it is one of those then it is Upper Ordovician in date, probably 451-443 mya (Cincinnati Stage).
You might like to have a look at this site for more information on the location and its associated fauna:
http://www.uga.edu/~strata/cincy/index.html
The following link is to the page on the above site which details the cephalopods found there. It has some excellent photographs should you wish to compare:
http://www.uga.edu/~strata/cincy/fauna/cephalopoda/cephalopoda.html
Best regards,
Phil
(P.S. Why is the place called Caesar's Creek? The Roman invasion of Cincinnati is a tale lost to time, it seems!)
