If it is that valuable, I wouldn't be putting any dummy ebay sales up.
You definitely want it valued (and even a valuer's certificate may cost you)
You also want to make sure that it is stored correctly. It would be awful if the antler material deteriorated because it was stored in the wrong cloth. PLus the steel will need maintaining. It is probably high carbon steel which has a tendancy to rust, and whatever you oil it with has to be compatable with the antler.
I don't know much about knives except to sharpen them and basic maintainance on hunting blades. But it would be a shame if your knife deteriorated and lost say half its value due to the antler material cracking.
Humidity and acid from handling it all become factors to its long term value.
