That depends on what you do with the information. Start with the price that you'd like to get and see if that draws any attention. Then lower it to the minimum acceptable price that you are willing to take.Can't disagree with you Dr G, just not very helpful! Thanks anyway.
If you hope to get the best price for the horn, it would probably be worth asking or even paying for assistance to get some pics that do the horn justice. People don't need $10,000 horns - unless the pictures convince them they do.Well, I've taken the advice given here and it's on ebay to test the waters.
Thanks to everyone who's replied.