I have a hard time putting a value on it, even just a personal value on it, when I don't know the caliber. But assuming it is in some sort of deer-elk like caliber (9.3x74 R or a .450 caliber) I, personally, would be thinking $3k give or take a little. If in a rimless cartridge, a little less. In a roe deer/ small whitetail caliber, for me, it would be quite a bit less. If a .22 rimfire then a bit more in line with the rimmed deer/elk calibers.
But that will tell you more about me than about the rifle.